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We study the physical properties of the ionized gas in local discs using the sample of 38 nearby ̃10<SUP>8.5-11.2</SUP> M<SUB>☉</SUB> Star-Forming Main-Sequence (SFMS) galaxies observed so far as part of the MUSE Atlas of Disks (MAD). Specifically, we use all strong emission lines in the MUSE wavelength range 4650-9300 Å to investigate the resolved ionized gas properties on ̃100 pc scales. This spatial resolution enables us to disentangle H II regions from the diffuse ionized gas (DIG) in the computation of gas metallicities and star formation rates (SFRs) of star-forming regions. The gas metallicities generally decrease with radius. The metallicity of the H II regions is on average ̃0.1 dex higher than that of the DIG, but the metallicity radial gradient in both components is similar. The mean metallicities within the inner galaxy cores correlate with the total stellar mass of the galaxies. On our < 100 pc scales, we find two correlations previously reported at kpc scales

By using a set of different star formation rate (SFR) indicators, including Wide-field Infrared Survey Explorer (WISE) mid-infrared and H α emission, we study the slope of the main sequence (MS) of local star-forming galaxies at stellar masses larger than 10^{10} M_{☉ }. The slope of the relation strongly depends on the SFR indicator used. In all cases, the local MS shows a bending at high stellar masses with respect to the slope obtained in the low-mass regime. While the distribution of galaxies in the upper envelope of the MS is consistent with a lognormal distribution, the lower envelope shows an excess of galaxies, which increases as a function of the stellar mass but varies as a function of the SFR indicator used. The scatter of the best lognormal distribution increases with stellar mass from ̃0.3 dex at 10^{10} M_{☉ } to ̃0.45 at 10^{11} M_{☉ }. The MS high-mass end is dominated by central galaxies of group-sized haloes with a red bulge and a disc redder than the lower mass counterparts. We argue that the MS bending in this region is due to two processes

One of the last missing pieces in the puzzle of galaxy formation and evolution through cosmic history is a detailed picture of the role of the cold gas supply in the star-formation process. Cold gas is the fuel for star formation, and thus regulates the buildup of stellar mass, both through the amount of material present through a galaxy's gas mass fraction, and through the efficiency at which it is converted to stars. Over the last decade, important progress has been made in understanding the relative importance of these two factors along with the role of feedback, and the first measurements of the volume density of cold gas out to redshift 4, (the "cold gas history of the Universe") has been obtained. To match the precision of measurements of the star formation and black-hole accretion histories over the coming decades, a two orders of magnitude improvement in molecular line survey speeds is required compared to what is possible with current facilities. Possible pathways towards such large gains include significant upgrades to current facilities like ALMA by 2030 (and beyond), and eventually the construction of a new generation of radio-to-millimeter wavelength facilities, such as the next generation Very Large Array (ngVLA) concept....

We use the results from the ALMA large program ASPECS, the spectroscopic survey in the Hubble Ultra Deep Field (HUDF), to constrain CO luminosity functions of galaxies and the resulting redshift evolution of $\rho$(H$_2$). The broad frequency range covered enables us to identify CO emission lines of different rotational transitions in the HUDF at $z>1$. We find strong evidence that the CO luminosity function evolves with redshift, with the knee of the CO luminosity function decreasing in luminosity by an order of magnitude from $\sim$2 to the local universe. Based on Schechter fits, we estimate that our observations recover the majority (up to $\sim$90%, depending on the assumptions on the faint end) of the total cosmic CO luminosity at $z$=1.0-3.1. After correcting for CO excitation, and adopting a Galactic CO-to-H$_2$ conversion factor, we constrain the evolution of the cosmic molecular gas density $\rho$(H$_2$)

We analyze the interstellar medium properties of a sample of sixteen bright CO line emitting galaxies identified in the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS) Large Program. This CO$-$selected galaxy sample is complemented by a couple of additional CO line emitters in the UDF that are identified based on their MUSE optical spectroscopic redshifts. The ASPECS CO$-$selected galaxies cover a larger range of star-formation rates and stellar masses compared to literature CO emitting galaxies at $z>1$ for which scaling relations have been established previously. Most of ASPECS CO-selected galaxies follow these established relations in terms of gas depletion timescales and gas fractions as a function of redshift, as well as the star-formation rate-stellar mass relation (`galaxy main sequence'). However, we find that $\sim30\%$ of the galaxies (5 out of 16) are offset from the galaxy main sequence at their respective redshift, with $\sim12\%$ (2 out of 16) falling below this relationship. Some CO-rich galaxies exhibit low star-formation rates, and yet show substantial molecular gas reservoirs, yielding long gas depletion timescales. Capitalizing on the well-defined cosmic volume probed by our observations, we measure the contribution of galaxies above, below, and on the galaxy main sequence to the total cosmic molecular gas density at different lookback times. We conclude that main sequence galaxies are the largest contributor to the molecular gas density at any redshift probed by our observations (z$\sim$1$-$3). The respective contribution by starburst galaxies above the main sequence decreases from z$\sim$2.5 to z$\sim$1, whereas we find tentative evidence for an increased contribution to the cosmic molecular gas density from the passive galaxies below the main sequence....

The ALMA SPECtroscopic Survey in the {\it Hubble} Ultra Deep Field is an ALMA large program that obtained a frequency scan in the 3\,mm band to detect emission lines from the molecular gas in distant galaxies. We here present our search strategy for emission lines and continuum sources in the HUDF. We compare several line search algorithms used in the literature, and critically account for the line-widths of the emission line candidates when assessing significance. We identify sixteen emission lines at high fidelity in our search. Comparing these sources to multi-wavelength data we find that all sources have optical/infrared counterparts. Our search also recovers candidates that have lower significance that can be used statistically to derive, e.g. the CO luminosity function. We apply the same detection algorithm to obtain a sample of six 3 mm continuum sources. All of these are also detected in the 1.2 mm continuum with optical/near-infrared counterparts. We use the continuum sources to compute 3 mm number counts in the sub-mJy regime, and find them to be higher by an order of magnitude than expected for synchrotron-dominated sources. However, the number counts are consistent with those derived at shorter wavelengths (0.85--1.3\,mm) once extrapolating to 3\,mm with a dust emissivity index of $\beta=1.5$, dust temperature of 35\,K and an average redshift of $z=2.5$. These results represent the best constraints to date on the faint end of the 3 mm number counts....

We discuss the nature and physical properties of gas-mass selected galaxies in the ALMA spectroscopic survey (ASPECS) of the Hubble Ultra Deep Field (HUDF). We capitalize on the deep optical integral-field spectroscopy from the MUSE HUDF Survey and multi-wavelength data to uniquely associate all 16 line-emitters, detected in the ALMA data without preselection, with rotational transitions of carbon monoxide (CO). We identify ten as CO(2-1) at $1 < z < 2$, five as CO(3-2) at $2 < z < 3$ and one as CO(4-3) at $z = 3.6$. Using the MUSE data as a prior, we identify two additional CO(2-1)-emitters, increasing the total sample size to 18. We infer metallicities consistent with (super-)solar for the CO-detected galaxies at $z \le 1.5$, motivating our choice of a Galactic conversion factor between CO luminosity and molecular gas mass for these galaxies. Using deep Chandra imaging of the HUDF, we determine an X-ray AGN fraction of 20% and 60% among the CO-emitters at $z \sim 1.4$ and $z \sim 2.6$, respectively. Being a CO-flux limited survey, ASPECS-LP detects molecular gas in galaxies on, above and below the main sequence (MS) at $z \sim 1.4$. For stellar masses $\ge 10^{10} (10^{10.5})$ M$_{\odot}$, we detect about 40% (50%) of all galaxies in the HUDF at $1 < z < 2$ ($2 < z < 3$). The combination of ALMA and MUSE integral-field spectroscopy thus enables an unprecedented view on MS galaxies during the peak of galaxy formation....

The role of feedback in triggering or quenching star formation and hence driving galaxy evolution can be directly studied with high-resolution integral field observations. The manifestation of feedback in shocks is particularly important to examine in galaxy mergers, where violent interactions of gas take place in the interstellar medium during the course of the galactic collision. As part of our effort to systematically study the local population of luminous infrared galaxies within the Great Observatories All-Sky LIRG Survey, we undertook the Keck OSIRIS AO LIRG Analysis observing campaign to study the gas dynamics in the inner kiloparsec regions of these systems at spatial scales of a few tens of pc. With high-resolution near-infrared adaptive optics-assisted integral field observations taken with OSIRIS on the Keck Telescopes, we employ near-infrared diagnostics such as Brγ and the rovibrationally excited H<SUB>2</SUB> lines to quantify the nuclear star formation rate and identify feedback associated with shocked molecular gas seen in 21 nearby luminous infrared galaxies. Shocked molecular gas is preferentially found in the ultraluminous infrared systems but may also be triggered at a lower-luminosity, earlier merging stage. On circumnuclear scales, AGNs have a strong effect on heating the surrounding molecular gas, though their coupling is not simply driven by AGN strength but rather is complicated by orientation, dust shielding, density, and other factors. We find that nuclear star formation correlates with merger class and diminishing projected nuclear separations. These trends are largely consistent with the picture of merger-induced starbursts in the center of galaxy mergers....

We present a detailed census of galaxies in and around PC 217.96+32.3, a spectroscopically confirmed Coma analog at z = 3.78. Diverse galaxy types identified in the field include Lyα emitters (LAEs), massive star-forming galaxies, and ultramassive galaxies (≳ {10}<SUP>11</SUP> {M}<SUB>☉ </SUB>) which may have already halted their star formation. The sky distribution of the star-forming galaxies suggests the presence of a significant overdensity (δ <SUB>SFG</SUB> ≈ 8 ± 2), which is spatially offset from the previously confirmed members by 3-4 Mpc to the west. Candidate quiescent and post-starburst galaxies are also found in large excess (a factor of ̃8-15 higher surface density than the field’s), although their redshifts are less certain. We estimate that the total enclosed mass traced by the candidate star-forming galaxies is roughly comparable to that of PC 217.96+32.3 traced by the LAEs. We speculate that the true extent of PC 217.96+32.3 may be larger than previously known, half of which is missed by our LAE selection. Alternatively, the newly discovered overdensity may belong to another Coma progenitor not associated with PC 217.96+32.3. Expectations from theory suggest that both scenarios are equally unlikely (<1%) in the cosmic volume probed in our survey. If confirmed as a single structure, its total mass will be well in excess of Coma’s, making it an exceptionally large cosmic structure rarely seen even in large cosmological simulations. Finally, we find that the protocluster galaxies follow the same star formation rate-M <SUB>*</SUB> scaling relation as the field galaxies, suggesting that the environmental effect at z ̃ 4 is a subtle one at best for normal star-forming galaxies....

With the imminent launch of the JWST, the field of thermal-infrared (TIR) astronomy will enjoy a revolution. It is easy to imagine that all areas of infrared (IR) astronomy will be greatly advanced, but perhaps impossible to conceive of the new vistas that will be opened. To allow both follow-up JWST observations and a continuance of work started on the ground-based 8m's, we continue to plan the science cases and instrument design for a TIR imager and spectrometer for early operation on the TMT. We present the current status of our science cases and the instrumentation plans, harnessing expertise across the TMT partnership. This instrument will be proposed by the MICHI team as a second-generation instrument in any upcoming calls for proposals....

<BR /> Aims

Mid-infrared molecular hydrogen (H<SUB>2</SUB>) emission is a powerful cooling agent in galaxy mergers and in radio galaxies; it is a potential key tracer of gas evolution and energy dissipation associated with mergers, star formation, and accretion onto supermassive black holes. We detect mid-IR H<SUB>2</SUB> line emission in at least one rotational transition in 91% of the 214 Luminous Infrared Galaxies (LIRGs) observed with Spitzer as part of the Great Observatories All-sky LIRG Survey. We use H<SUB>2</SUB> excitation diagrams to estimate the range of masses and temperatures of warm molecular gas in these galaxies. We find that LIRGs in which the IR emission originates mostly from the Active Galactic Nuclei (AGN) have about 100 K higher H<SUB>2</SUB> mass-averaged excitation temperatures than LIRGs in which the IR emission originates mostly from star formation. Between 10% and 15% of LIRGs have H<SUB>2</SUB> emission lines that are sufficiently broad to be resolved or partially resolved by the high-resolution modules of Spitzer’s Infrared Spectrograph (IRS). Those sources tend to be mergers and contain AGN. This suggests that a significant fraction of the H<SUB>2</SUB> line emission is powered by AGN activity through X-rays, cosmic rays, and turbulence. We find a statistically significant correlation between the kinetic energy in the H<SUB>2</SUB> gas and the H<SUB>2</SUB> to IR luminosity ratio. The sources with the largest warm gas kinetic energies are mergers. We speculate that mergers increase the production of bulk inflows leading to observable broad H<SUB>2</SUB> profiles and possibly denser gas....

We analyze Chandra X-ray observatory data for a sample of 63 luminous infrared galaxies (LIRGs), sampling the lower-infrared luminosity range of the Great Observatories All-Sky LIRG survey (GOALS), which includes the most luminous infrared selected galaxies in the local Universe. X-rays are detected for 84 individual galaxies within the 63 systems, for which arcsecond resolution X-ray images, fluxes, infrared and X-ray luminosities, spectra and radial profiles are presented. Using X-ray and mid-infrared (MIR) selection criteria, we find AGN in (31 ± 5)% of the galaxy sample, compared to the (38 ± 6)% previously found for GOALS galaxies with higher infrared luminosities (C-GOALS I). Using MIR data, we find that (59 ± 9)% of the X-ray selected AGN in the full C-GOALS sample do not contribute significantly to the bolometric luminosity of the host galaxy. Dual AGN are detected in two systems, implying a dual AGN fraction in systems that contain at least one AGN of (29 ± 14)%, compared to the (11 ± 10)% found for the C-GOALS I sample. Through analysis of radial profiles, we derive that most sources, and almost all AGN, in the sample are compact, with half of the soft X-ray emission generated within the inner ̃1 kpc. For most galaxies, the soft X-ray sizes of the sources are comparable to those of the MIR emission. We also find that the hard X-ray faintness previously reported for the bright C-GOALS I sources is also observed in the brightest LIRGs within the sample, with L<SUB>FIR</SUB> > 8 × 10<SUP>10</SUP> L<SUB>☉</SUB>....

Galaxy mergers and gas accretion from the cosmic web drove the growth of galaxies and their central black holes at early epochs. We report spectroscopic imaging of a multiple merger event in the most luminous known galaxy, WISE J224607.56-052634.9 (W2246-0526), a dust-obscured quasar at redshift 4.6, 1.3 billion years after the Big Bang. Far-infrared dust continuum observations show three galaxy companions around W2246-0526 with disturbed morphologies, connected by streams of dust likely produced by the dynamical interaction. The detection of tidal dusty bridges shows that W2246-0526 is accreting its neighbors, suggesting that merger activity may be a dominant mechanism through which the most luminous galaxies simultaneously obscure and feed their central supermassive black holes....

Change history

The role of feedback in triggering or quenching star formation and hence driving galaxy evolution can be directly studied with high resolution integral field observations. The manifestation of feedback in shocks is particularly important to examine in galaxy mergers, where violent interactions of gas takes place in the interstellar medium during the course of the galactic collision. As part of our effort to systematically study the local population of luminous infrared galaxies within the Great Observatories All-Sky LIRG Survey, we undertook the Keck OSIRIS AO LIRG Analysis observing campaign to study the gas dynamics in the inner kiloparsec regions of these systems at spatial scales of a few 10s of parsecs. With high-resolution near-infrared adaptive optics-assisted integral-field observations taken with OSIRIS on the Keck Telescopes, we employ near-infrared diagnostics such as Brg and the ro-vibrationally excited H2 lines to quantify the nuclear star formation rate and identify feedback associated with shocked molecular gas seen in 21 nearby luminous infrared galaxies. Shocked molecular gas is preferentially found in the ultraluminous infrared systems, but may also be triggered at a lower luminosity, earlier merging stage. On circumnuclear scales, AGN have a strong effect on heating the surrounding molecular gas, though their coupling is not simply driven by AGN strength but rather is complicated by orientation, dust shielding, density, and other factors. We find that the nuclear star formation correlates with merger class and diminishing projected nuclear separations. These trends are largely consistent with the picture of merger-induced starbursts within the center of galaxy mergers....

Star-forming galaxies have been found to follow a relatively tight relation between stellar mass (M<SUB>*</SUB>) and star formation rate (SFR), dubbed the "star formation sequence". A turnover in the sequence has been observed, where galaxies with M<SUB>*</SUB> < 10<SUP>10</SUP> M<SUB>☉</SUB> follow a steeper relation than their higher mass counterparts, suggesting that the low-mass slope is (nearly) linear. In this paper, we characterise the properties of the low-mass end of the star formation sequence between 7 ≤ log M<SUB>*</SUB>[M<SUB>☉</SUB>] ≤ 10.5 at redshift 0.11 < z < 0.91. We use the deepest MUSE observations of the Hubble Ultra Deep Field and the Hubble Deep Field South to construct a sample of 179 star-forming galaxies with high signal-to-noise emission lines. Dust-corrected SFRs are determined from Hβ λ4861 and Hα λ6563. We model the star formation sequence with a Gaussian distribution around a hyperplane between logM<SUB>*</SUB>, logSFR, and log(1 + z), to simultaneously constrain the slope, redshift evolution, and intrinsic scatter. We find a sub-linear slope for the low-mass regime where log SFR [M<SUB>☉</SUB>yr<SUP>-1</SUP>] = 0.83<SUP>+0.07</SUP><SUB>-0.06</SUB> log M<SUB>*</SUB>[M<SUB>☉</SUB>]+1.74<SUP>+0.66</SUP><SUB>-0.68</SUB> log(1 + z), increasing with redshift. We recover an intrinsic scatter in the relation of σ<SUB>intr</SUB> = 0.44<SUP>+0.05</SUP><SUB>-0.04</SUB>, dex, larger than typically found at higher masses. As both hydrodynamical simulations and (semi-)analytical models typically favour a steeper slope in the low-mass regime, our results provide new constraints on the feedback processes which operate preferentially in low-mass halos. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programme IDs ID 060.A-9100(C), 094.A-2089(B), 095.A-0010(A), 096.A-0045(A), and 096.A-0045(B)....

We present high-resolution (0.″17 × 0.″14) Atacama Large Millimeter/submillimeter Array (ALMA) observations of the CO (6-5) line and 435 μm dust continuum emission within a ̃9″ × 9″ area centered on the nucleus of the galaxy NGC 5135. NGC 5135 is a well-studied luminous infrared galaxy that also harbors a Compton-thick active galactic nucleus (AGN). At the achieved resolution of 48 × 40 pc, the CO (6-5) and dust emissions are resolved into gas “clumps” along the symmetrical dust lanes associated with the inner stellar bar. The clumps have radii in the range of ̃45-180 pc and CO (6-5) line widths of ̃60-88 {km} { { {s } }}<SUP>-1</SUP>. The CO (6-5) to dust continuum flux ratios vary among the clumps and show an increasing trend with the [Fe II]/Brγ ratios, which we interpret as evidence for supernova-driven shocked gas providing a significant contribution to the CO (6-5) emission. The central AGN is undetected in continuum, nor is it detected in CO (6-5) if its line velocity width is no less than ̃ 40 {km} { { {s } }}<SUP>-1</SUP>. We estimate that the AGN contributes at most 1% of the integrated CO (6-5) flux of 512 ± 24 Jy {km} { { {s } }}<SUP>-1</SUP> within the ALMA field of view, which in turn accounts for ̃32% of the CO (6-5) flux of the whole galaxy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc....

Our imaging data sets come from several surveys. MIPS 24um data come from the GOODS-Spitzer program (PI

We present a study of the [O III]/[O II] ratios of star-forming galaxies drawn from Multi-Unit Spectroscopic Explorer (MUSE) data spanning a redshift range 0.28 < z < 0.85. Recently discovered Lyman continuum (LyC) emitters have extremely high oxygen line ratios

Galaxies are surrounded by large reservoirs of gas, mostly hydrogen, that are fed by inflows from the intergalactic medium and by outflows from galactic winds. Absorption-line measurements along the lines of sight to bright and rare background quasars indicate that this circumgalactic medium extends far beyond the starlight seen in galaxies, but very little is known about its spatial distribution. The Lyman-α transition of atomic hydrogen at a wavelength of 121.6 nanometres is an important tracer of warm (about 10<SUP>4</SUP> kelvin) gas in and around galaxies, especially at cosmological redshifts greater than about 1.6 at which the spectral line becomes observable from the ground. Tracing cosmic hydrogen through its Lyman-α emission has been a long-standing goal of observational astrophysics<SUP>1-3</SUP>, but the extremely low surface brightness of the spatially extended emission is a formidable obstacle. A new window into circumgalactic environments was recently opened by the discovery of ubiquitous extended Lyman-α emission from hydrogen around high-redshift galaxies<SUP>4,5</SUP>. Such measurements were previously limited to especially favourable systems<SUP>6-8</SUP> or to the use of massive statistical averaging<SUP>9,10</SUP> because of the faintness of this emission. Here we report observations of low-surface-brightness Lyman-α emission surrounding faint galaxies at redshifts between 3 and 6. We find that the projected sky coverage approaches 100 per cent. The corresponding rate of incidence (the mean number of Lyman-α emitters penetrated by any arbitrary line of sight) is well above unity and similar to the incidence rate of high-column-density absorbers frequently detected in the spectra of distant quasars<SUP>11-14</SUP>. This similarity suggests that most circumgalactic atomic hydrogen at these redshifts has now been detected in emission....

Context. Deep mid-infrared (MIR) surveys have revealed numerous strongly star-forming galaxies at redshift z ≲ 2. Their MIR fluxes are produced by a combination of continuum and polycyclic aromatic hydrocarbon (PAH) emission features. The PAH features can dominate the total MIR flux, but are difficult to measure without spectroscopy. <BR /> Aims

The physical origin of the near-ultraviolet Mg II emission remains an underexplored domain, unlike more typical emission lines that are detected in the spectra of star-forming galaxies. We explore the nebular and physical properties of a sample of 381 galaxies between 0.70 < z < 2.34 drawn from the MUSE Hubble Ultra Deep Survey. The spectra of these galaxies show a wide variety of profiles of the Mg II λλ2796, 2803 resonant doublet, from absorption to emission. We present a study on the main drivers for the detection of Mg II emission in galaxy spectra. By exploiting photoionization models, we verified that the emission-line ratios observed in galaxies with Mg II in emission are consistent with nebular emission from HII regions. From a simultaneous analysis of MUSE spectra and ancillary Hubble Space Telescope information through spectral energy distribution fitting, we find that galaxies with Mg II in emission have lower stellar masses, smaller sizes, bluer spectral slopes, and lower optical depth than those with absorption. This leads us to suggest that Mg II emission is a potential tracer of physical conditions that are not merely related to those of the ionized gas. We show that these differences in Mg II emission and absorption can be explained in terms of a higher dust and neutral gas content in the interstellar medium (ISM) of galaxies showing Mg II in absorption, which confirms the extreme sensitivity of Mg II to the presence of the neutral ISM. We conclude with an analogy between the Mg II doublet and the Ly α line that lies in their resonant nature. Further investigations with current and future facilities, including the James Webb Space Telescope, are promising because the detection of Mg II emission and its potential connection with Lyα could provide new insights into the ISM content in the early Universe. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programs 094.A-0289(B), 095.A-0010(A), 096.A-0045(A) and 096.A-0045(B)....

Using an ultra-deep blind survey with the MUSE integral field spectrograph on the European Southern Observatory Very Large Telescope, we obtain spectroscopic redshifts to a depth never before explored

We present AKARI 2.5-5 μm spectra of 145 local luminous infrared galaxies (LIRG; L<SUB>IR</SUB> ≥ 10<SUP>11</SUP> L<SUB>☉</SUB>) in the Great Observatories All-sky LIRG Survey (GOALS). In all of the spectra, we measure the line fluxes and equivalent widths (EQWs) of the polycyclic aromatic hydrocarbon (PAH) at 3.3 μm and the hydrogen recombination line Brα at 4.05 μm, with apertures matched to the slit sizes of the Spitzer low-resolution spectrograph and with an aperture covering ̃95% of the total flux in the AKARI two-dimensional (2D) spectra. The star formation rates (SFRs) derived from the Brα emission measured in the latter aperture agree well with SFRs estimated from L<SUB>IR</SUB>, when the dust extinction correction is adopted based on the 9.7 μm silicate absorption feature. Together with the Spitzer Infrared Spectrograph (IRS) 5.2-38 μm spectra, we are able to compare the emission of the PAH features detected at 3.3 μm and 6.2 μm. These are the two most commonly used near/mid-infrared indicators of starburst or active galactic nucleus (AGN) dominated galaxies. We find that the 3.3 μm and 6.2 μm PAH EQWs do not follow a linear correlation and at least a third of the galaxies classified as AGN-dominated sources using the 3.3 μm feature are classified as starbursts based on the 6.2 μm feature. These galaxies have a bluer continuum slope than galaxies that are indicated to be starburst-dominated by both PAH features. The bluer continuum emission suggests that their continuum is dominated by stellar emission rather than hot dust. We also find that the median Spitzer/IRS spectra of these sources are remarkably similar to the pure starburst-dominated sources indicated by high PAH EQWs in both 3.3 μm and 6.2 μm. Based on these results, we propose a revised starburst/AGN diagnostic diagram using 2-5 μm data: the 3.3 μm PAH EQW and the continuum color, F<SUB>ν</SUB>(4.3 μm)/F<SUB>ν</SUB>(2.8 μm). We use the AKARI and Spitzer spectra to examine the performance of our new starburst/AGN diagnostics and to estimate 3.3 μm PAH fluxes using the James Webb Space Telescope (JWST) photometric bands in the redshift range 0 < z < 5. Of the known PAH features and mid-infrared high ionization emission lines used as starburst/AGN indicators, only the 3.3 μm PAH feature is observable with JWST at z > 3.5, because the rest of the features at longer wavelengths fall outside the JWST wavelength coverage. Full Table 1 and data associated to Fig. 9 are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/vizbin/qcat?J/A+A/617/A130">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/617/A130</A>...

The Lyman alpha (Ly α) line of Hydrogen is a prominent feature in the spectra of star-forming galaxies, usually redshifted by a few hundreds of km s<SUP>-1</SUP> compared to the systemic redshift. This large offset hampers follow-up surveys, galaxy pair statistics, and correlations with quasar absorption lines when only Ly α is available. We propose diagnostics that can be used to recover the systemic redshift directly from the properties of the Ly α line profile. We use spectroscopic observations of Ly α emitters for which a precise measurement of the systemic redshift is available. Our sample contains 13 sources detected between z ≈ 3 and z ≈ 6 as part of various multi-unit spectroscopic explorer guaranteed time observations. We also include a compilation of spectroscopic Ly α data from the literature spanning a wide redshift range (z ≈ 0-8). First, restricting our analysis to double-peaked Ly α spectra, we find a tight correlation between the velocity offset of the red peak with respect to the systemic redshift, V_peak^red, and the separation of the peaks. Secondly, we find a correlation between V_peak^red and the full width at half-maximum of the Ly α line. Fitting formulas to estimate systemic redshifts of galaxies with an accuracy of ≤100 km s<SUP>-1</SUP>, when only the Ly α emission line is available, are given for the two methods....

We report the discovery and spectroscopic confirmation of a very large star-forming galaxy, G6025, at {z}<SUB>spec</SUB>} =3.721+/- 0.003. In the rest frame ≈2100 Å, G6025 subtends ≈24 kpc in physical extent when measured from the 1.5σ isophote, in agreement with the parametric size measurements that yield a half-light radius of 4.9 ± 0.5 kpc and a semimajor axis of 12.5 ± 0.1 kpc. It is also very UV-luminous (≈ 5{L}<SUB>UV</SUB>,z̃ 4}<SUP>* </SUP>) and young (≈140 ± 60 Myr). Despite its unusual size and luminosity, the stellar population parameters and dust reddening ({M}<SUB>star</SUB>}̃ {M}<SUB>z̃ 4</SUB><SUP>* </SUP> and E(B - V) ̃ 0.18 ± 0.05) estimated from the integrated light are similar to those of smaller galaxies at comparable redshifts. The ground-based morphology and spectroscopy show two dominant components, both located off-center, embedded in more diffuse emission. We speculate that G6025 may be a scaled-up version of chain galaxies seen in deep HST imaging or, alternatively, a nearly equal-mass merger involving two super-L* galaxies in its early stage. It lies close to but not within a known massive protocluster at z = 3.78. We find four companions within 6 Mpc from G6025, two of which lie within 1.6 Mpc. While the limited sensitivity of the existing spectroscopy does not allow us to robustly characterize the local environment of G6025, it likely resides in a locally overdense environment. The luminosity, size, and youth of G6025 make it uniquely suited to study the early formation of massive galaxies in the universe. This paper is based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership

With the imminent launch of the JWST, the field of thermal-infrared (TIR) astronomy will enjoy a revolution. It is easy to imagine that all areas of infrared (IR) astronomy will be greatly advanced, but perhaps impossible to conceive of the new vistas that will be opened. To allow both follow-up JWST observations and a continuance of work started on the ground-based 8m's, we continue to plan the science cases and instrument design for a TIR imager and spectrometer for early operation on the TMT. We present the current status of our science cases and the instrumentation plans, harnessing expertise across the TMT partnership. This instrument will be proposed by the MICHI team as a second-generation instrument in any upcoming calls for proposals....

We present the table of line flux and equivalent width (EQW) of 3.3um polycyclic aromatic hydrocarbon (PAH) and Brackett-alpha, and the continuum color of Fnu(4.3um)/Fnu(2.8um) measured in 145 AKARI spectra using the 4.4-arcsecond radius aperture (Table 1). The EQW of 6.2-micron PAH from Stierwalt et al. (2013, Cat. J/ApJS/206/1) is presented together. We also publish the data of the median SEDs of starburst- and AGN-dominated LIRGs as shown in Figure 9. (3 data files)....

Recent theoretical models suggest that the early phase of galaxy formation could involve an epoch when galaxies are gas rich but inefficient at forming stars

We have obtained FIR spectroscopic observations for 200 luminous infrared galaxies (LIRG) systems from the Great Observatories All-Sky LIRG Survey (GOALS; Armus+ 2009PASP..121..559A) using the Integral Field Spectrometer (IFS) of the PACS instrument on board Herschel. Since some targets contain multiple components, there are 241 individual galaxies with available spectra in at least one emission line. Most of the data were collected as part of our OT1 and OT2 programs (OT1<SUB>larmus</SUB>1, OT2<SUB>larmus</SUB>1; P.I.

Star formation rate (SFR) is important to quantify for galaxies because it provides a method for reconstructing the cosmic history of star formation in the universe. H is frequently utilized in SFR studies, however, this hydrogen recombination line is strongly affected by interstellar dust extinction. For a sample of 23 galaxies, we report Br alpha/H alpha and H alpha/H beta measurements and found that for most of our sample, the traditional Balmer decrement, H alpha/H beta, unexpectedly gives higher A(sub V) than when Br alpha/H alpha is used when we adopt the Calzetti extinction law. In addition, galaxies with the highest specific star formation rate (SSFR) on average have higher A(sub V)(Br alpha/H alpha) than A(sub V)(H alpha/H beta). However, we do not find a clear trend of the line ratios against L(sub IR) or IR/UV....

We have combined AKARI 2.5-5 micrometers and Spitzer 5.2-38 micrometers spectra of 145 local luminous infrared galaxies (LIRGs) drawn from the Great Observatories All-sky LIRG Survey (GOALS). The equivalent widths (EQWs) of the polycyclic aromatic hydrocarbon (PAH) emission features detected at 3.3 micrometers and 6.2 micrometers, the two most commonly used indicators for classifying the central energy sources (starburst or active galactic nucleus, AGN), do not appear to be linearly correlated. Moreover, about 30% of the AGN-dominated galaxies classified by the 3.3 micrometers PAH EQW are, on the contrary, suggested to be starburst-dominated galaxies by the 6.2 micrometers PAH EQW. We find that the Spitzer spectra of the sources with low 3.3 micrometers PAH EQW but high 6.2 micrometers PAH EQW are remarkably similar to the spectra of pure starburst sources. However, their 2-5 micrometers continua in AKARI spectra are much bluer, suggesting that the continuum is dominated by stellar emission rather than hot dust emission. Based on these results, we suggest a revised diagnostic using the 3.3 micrometers PAH EQW and the continuum color. We also report on a possible diagnostic with the capabilities of the James Webb Space Telescope (JWST) based on the results from the AKARI and Spitzer data....

We aim to study star-forming galaxies by using a blind spectroscopic survey at mid-infrared (MIR) wavelengths to understand evolution of their star formation rate (SFR) and specific SFR (SFR per stellar mass) up to z in the order of 0.5, by paying particular attention to their Polycyclic Aromatic Hydrocarbon (PAH) properties. We conducted a low-resolution (R approximately equal to 50) slitless spectroscopic survey at 5-13 micrometers of 9 micrometers flux-selected sources (approximately greater than 0.3 mJy) around the North Ecliptic Pole with the Infrared Camera (IRC) onboard AKARI. We identified 48 PAH galaxies with PAH 6.2, 7.7, and 8.6 micrometers features at z approximately less than 0.5. The rest-frame optical-MIR spectral energy distributions (SEDs) based on CFHT and AKARI/IRC imaging are produced and analyzed in conjunction with the PAH spectroscopy. The rest-frame SEDs of all PAH galaxies have a universal shape with stellar and 7.7 micrometers (PAH) bumps, except that the PAH enhancement (luminosity ratio of the 7.7 micrometers PAH feature over the 3.5 micrometers stellar bump) significantly varies as a function of the PAH luminosities. We identified a PAH-enhanced population at z approximately less than 0.35, whose SEDs and luminosities are typical of luminous infrared galaxies. They show particularly larger PAH enhancement at high luminosity, implying that they are vigorous star-forming galaxies with elevated specific SFR. Our composite starburst model that combines a young and dusty starburst with a very old population can successfully reproduce most SED characteristics....

We present a new technique to measure multi-wavelength “super-deblended” photometry from highly confused images, which we apply to Herschel and ground-based far-infrared (FIR) and (sub-)millimeter (mm) data in the northern field of the Great Observatories Origins Deep Survey. There are two key novelties. First, starting with a large database of deep Spitzer 24 μm and VLA 20 cm detections that are used to define prior positions for fitting the FIR/submm data, we perform an active selection of useful priors independently at each frequency band, moving from less to more confused bands. Exploiting knowledge of redshift and all available photometry, we identify hopelessly faint priors that we remove from the fitting pool. This approach significantly reduces blending degeneracies and allows reliable photometry to be obtained for galaxies in FIR+mm bands. Second, we obtain well-behaved, nearly Gaussian flux density uncertainties, individually tailored to all fitted priors for each band. This is done by exploiting extensive simulations that allow us to calibrate the conversion of formal fitting uncertainties to realistic uncertainties, depending on directly measurable quantities. We achieve deeper detection limits with high fidelity measurements and uncertainties at FIR+mm bands. As an illustration of the utility of these measurements, we identify 70 galaxies with z≥slant 3 and reliable FIR+mm detections. We present new constraints on the cosmic star formation rate density at 3< z< 6, finding a significant contribution from z≥slant 3 dusty galaxies that are missed by optical-to-near-infrared color selection. Photometric measurements for 3306 priors, including more than 1000 FIR+mm detections, are released publicly with our catalog....

We present an analysis of Multi Unit Spectroscopic Explorer (MUSE) observations obtained on themassive Frontier Fields (FFs) cluster A2744. This new data set covers the entire multiply imaged region around the cluster core. The combined catalogue consists of 514 spectroscopic redshifts (with 414 new identifications). We use this redshift information to perform a strong-lensing analysis revising multiple images previously found in the deep FF images, and add three new MUSE-detected multiply imaged systems with no obvious Hubble Space Telescope counterpart. The combined strong-lensing constraints include a total of 60 systems producing 188 images altogether, out of which 29 systems and 83 images are spectroscopically confirmed, making A2744 one of the most well-constrained clusters to date. Thanks to the large amount of spectroscopic redshifts, we model the influence of substructures at larger radii, using a parametrization including two cluster-scale components in the cluster core and several group scale in the outskirts. The resulting model accurately reproduces all the spectroscopic multiple systems, reaching an rms of 0.67 arcsec in the image plane. The large number of MUSE spectroscopic redshifts gives us a robust model, which we estimate reduces the systematic uncertainty on the 2D mass distribution by up to similar to 2.5 times the statistical uncertainty in the cluster core. In addition, from a combination of the parametrization and the set of constraints, we estimate the relative systematic uncertainty to be up to 9 per cent at 200 kpc.

Cosmological simulations suggest that most of the matter in the Universe is distributed along filaments connecting galaxies. Illuminated by the cosmic UV background (UVB), these structures are expected to glow in fluorescent Ly α emission with a surface brightness (SB) that is well below current limits for individual detections. Here, we perform a stacking analysis of the deepest MUSE/VLT data using three-dimensional regions (subcubes) with orientations determined by the position of neighbouring Ly α galaxies at 3 < z < 4. Our method increase the probability of detecting filamentary Ly α emission, provided that these structures are Lyman-limit systems (LLSs). By stacking 390 oriented subcubes we reach a 2σ sensitivity level of SB ≈ 0.44 × 10<SUP>-20</SUP> erg s<SUP>-1</SUP> cm<SUP>-2</SUP> arcsec<SUP>-2</SUP> in an aperture of 1 arcsec<SUP>2</SUP> × 6.25 Å, three times below the expected fluorescent Ly α signal from the Haardt & Madau UVB at z ̃ 3.5. No detectable emission is found on intergalactic scales, implying that at least two thirds of our subcubes do not contain oriented LLSs. On the other hand, significant emission is detected in the circumgalactic medium (CGM) in the direction of the neighbours. The signal is stronger for galaxies with a larger number of neighbours and appears to be independent of any other galaxy properties. We estimate that preferentially oriented satellite galaxies cannot contribute significantly to this signal, suggesting instead that gas densities in the CGM are typically larger in the direction of neighbouring galaxies on cosmological scales....

We have conducted a two-layered spectroscopic survey (1' x 1' ultra deep and 3' x 3' deep regions) in the Hubble Ultra Deep Field (HUDF) with the Multi Unit Spectroscopic Explorer (MUSE). The combination of a large field of view, high sensitivity, and wide wavelength coverage provides an order of magnitude improvement in spectroscopically confirmed redshifts in the HUDF; i.e., 1206 secure spectroscopic redshifts for HST continuum selected objects, which corresponds to 15% of the total (7904). The redshift distribution extends well beyond z > 3 and to HST/F775W magnitudes as faint as approximate to 30 mag (AB, 1 sigma). In addition, 132 secure redshifts were obtained for sources with no HST counterparts that were discovered in the MUSE data cubes by a blind search for emission-line features. In total, we present 1338 high quality redshifts, which is a factor of eight increase compared with the previously known spectroscopic redshifts in the same field. We assessed redshifts mainly with the spectral features [O II] at z < 1.5 (473 objects) and Ly alpha at 2.9 < z < 6.7 (692 objects). With respect to F775W magnitude, a 50% completeness is reached at 26.5 mag for ultra deep and 25.5 mag for deep fields, and the completeness remains greater than or similar to 20% up to 28-29 mag and approximate to 27 mag, respectively. We used the determined redshifts to test continuum color selection (dropout) diagrams of high-z galaxies. The selection condition for F336W dropouts successfully captures approximate to 80% of the targeted z similar to 2.7 galaxies. However, for higher redshift selections (F435W, F606W, and F775W dropouts), the success rates decrease to approximate to 20-40%. We empirically redefine the selection boundaries to make an attempt to improve them to approximate to 60%. The revised boundaries allow bluer colors that capture Ly alpha emitters with high Ly alpha equivalent widths falling in the broadbands used for the color-color selection. Along with this paper, we release the redshift and line flux catalog.

We present the MUSE Hubble Ultra Deep Survey, a mosaic of nine MUSE fields covering 90% of the entire HUDF region with a 10-h deep exposure time, plus a deeper 31-h exposure in a single 1.15 arcmin<SUP>2</SUP> field. The improved observing strategy and advanced data reduction results in datacubes with sub-arcsecond spatial resolution (0.̋65 at 7000 Å) and accurate astrometry (0.̋07 rms). We compare the broadband photometric properties of the datacubes to HST photometry, finding a good agreement in zeropoint up to m<SUB>AB</SUB> = 28 but with an increasing scatter for faint objects. We have investigated the noise properties and developed an empirical way to account for the impact of the correlation introduced by the 3D drizzle interpolation. The achieved 3σ emission line detection limit for a point source is 1.5 and 3.1 × 10<SUP>-19</SUP> erg s<SUP>-1</SUP> cm<SUP>-2</SUP> for the single ultra-deep datacube and the mosaic, respectively. We extracted 6288 sources using an optimal extraction scheme that takes the published HST source locations as prior. In parallel, we performed a blind search of emission line galaxies using an original method based on advanced test statistics and filter matching. The blind search results in 1251 emission line galaxy candidates in the mosaic and 306 in the ultradeep datacube, including 72 sources without HST counterparts (m<SUB>AB</SUB> > 31). In addition 88 sources missed in the HST catalog but with clear HST counterparts were identified. This data set is the deepest spectroscopic survey ever performed. In just over 100 h of integration time, it provides nearly an order of magnitude more spectroscopic redshifts compared to the data that has been accumulated on the UDF over the past decade. The depth and high quality of these datacubes enables new and detailed studies of the physical properties of the galaxy population and their environments over a large redshift range. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programs 094.A-0289(B), 095.A-0010(A), 096.A-0045(A) and 096.A-0045(B)....

Fitted parameters, measurements and general properties of the 145 Lyman-alpha emitters surrounded by a halo in the MUSE UDF data. (1 data file)....

Galaxies evolve through a combination of secular processes, such as cold gas accretion, and nonsecular processes, such as galactic mergers, which can trigger massive starbursts and powerful AGN. JWST will transform our understanding of galactic evolution, providing a detailed look at the physics of star formation and black hole growth in nearby and distant galaxies. By using NIRSPEC, NIRCAM and MIRI, we will create a rich dataset for understanding the dynamics and energetics of the ISM on scales of 50-100pc in the nuclei of local Luminous Infrared Galaxies (LIRGs). Our targets cover a range of starburst-to-AGN power and IR spectral properties, and are all visible to JWST over the first 5 months of Cycle-1. We will target each nucleus with the NIRSPEC and MIRI IFUs to cover the full spectral range from 0.96-29 microns, and obtain deep, wide-field NIRCAM and MIRI images in the F150W, F200W, F335M, F444W, F560W, F770W and F1500W filters. The total time for our proposal (NOI #80) is 30.97hrs. Our science-enabling products include multi-wavelength, ancillary datasets from Spitzer, ALMA, JVLA, AKARI and HST, valuable cross-calibration infrared data from Spitzer and AKARI, together with custom spectral fitting software which we will deliver and use to analyze the JWST spectral cubes. The proposed observations will be scientifically compelling in their own right, and they will also demonstrate to the community how to fully explore the power of JWST to unravel the complex galactic ecosystems in nearby active and starburst galaxies. This proposal will set the stage for more extensive studies of active and starburst galaxies at low and high-redshift in Cycle-2 and beyond....

The C III] lambda lambda 1907, 1909 emission doublet has been proposed as an alternative to Lyman-alpha in redshift confirmations of galaxies at z greater than or similar to 6 since it is not attenuated by the largely neutral intergalactic medium at these redshifts and is believed to be strong in the young, vigorously star-forming galaxies present at these early cosmic times. We present a statistical sample of 17 C III]-emitting galaxies beyond z similar to 1.5 using similar to 30 h deep VLT/MUSE integral field spectroscopy covering 2 square arcminutes in the Hubble Deep field South (HDFS) and Ultra Deep Field (UDF), achieving C III] sensitivities of similar to 2 x 10(-17) erg s(-1) cm(-2) in the HDFS and similar to 7 x 10(-18) erg s(-1) cm(-2) in the UDF. The rest-frame equivalent widths range from 2 to 19 angstrom. These 17 galaxies represent similar to 3% of the total sample of galaxies found between 1.5 less than or similar to z less than or similar to 4. They also show elevated star formation rates, lower dust attenuation, and younger mass-weighted ages than the general population of galaxies at the same redshifts. Combined with deep slitless grism spectroscopy from the HST/WFC3 in the UDF, we can tie the rest-frame ultraviolet C III] emission to rest-frame optical emission lines, namely [O III] lambda 5007, finding a strong correlation between the two. Down to the flux limits that we observe (similar to 1 x 10(-18) erg s(-1) cm(-2) with the grism data in the UDF), all objects with a rest-frame [O III] lambda lambda 4959, 5007 equivalent width in excess of 250 angstrom, the so-called extreme emission line galaxies, have detections of C III] in our MUSE data. More detailed studies of the C III]-emitting population at these intermediate redshifts will be crucial to understand the physical conditions in galaxies at early cosmic times and to determine the utility of C III] as a redshift tracer.

We present rest-frame Lyα equivalent widths (EW<SUB>0</SUB>) of 417 Lyα emitters (LAEs) detected with Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) at 2.9 <z< 6.6 in the Hubble Ultra Deep Field. Based on the deep MUSE spectroscopy and ancillary Hubble Space Telescope (HST) photometry data, we carefully measured EW<SUB>0</SUB> values taking into account extended Lyα emission and UV continuum slopes (β). Our LAEs reach unprecedented depths, both in Lyα luminosities and UV absolute magnitudes, from log (L<SUB>Lyα</SUB>/erg s<SUP>-1</SUP>) 41.0 to 43.0 and from M<SUB>UV</SUB> -16 to -21 (0.01-1.0 L<SUP>*</SUP><SUB>z=3</SUB>). The EW<SUB>0</SUB> values span the range of 5 to 240 Å or larger, and their distribution can be well fitted by an exponential law N = N<SUB>0</SUB> exp(-EW<SUB>0</SUB>/w<SUB>0</SUB>). Owing to the high dynamic range in M<SUB>UV</SUB>, we find that the scale factor, w<SUB>0</SUB>, depends on M<SUB>UV</SUB> in the sense that including fainter M<SUB>UV</SUB> objects increases w<SUB>0</SUB>, i.e., the Ando effect. The results indicate that selection functions affect the EW<SUB>0</SUB> scale factor. Taking these effects into account, we find that our w<SUB>0</SUB> values are consistent with those in the literature within 1σ uncertainties at 2.9 < z < 6.6 at a given threshold of M<SUB>UV</SUB> and L<SUB>Lyα</SUB>. Interestingly, we find 12 objects with EW<SUB>0</SUB>> 200 Å above 1σ uncertainties. Two of these 12 LAEs show signatures of merger or AGN activity

We report the detection of extended Lyα haloes around 145 individual star-forming galaxies at redshifts 3 ≤ z ≤ 6 in the Hubble Ultra Deep Field observed with the Multi-Unit Spectroscopic Explorer (MUSE) at ESO-VLT. Our sample consists of continuum-faint (- 15 ≥ M<SUB>UV</SUB> ≥ -22) Lyα emitters (LAEs). Using a 2D, two-component (continuum-like and halo) decomposition of Lyα emission assuming circular exponential distributions, we measure scale lengths and luminosities of Lyα haloes. We find that 80% of our objects having reliable Lyα halo measurements show Lyα emission that is significantly more extended than the UV continuum detected by HST (by a factor ≈4 to >20). The median exponential scale length of the Lyα haloes in our sample is ≈4.5 kpc with a few haloes exceeding 10 kpc. By comparing the maximal detected extent of the Lyα emission with the predicted dark matter halo virial radii of simulated galaxies, we show that the detected Lyα emission of our selected sample of Lyα emitters probes a significant portion of the cold circum-galactic medium of these galaxies (>50% in average). This result therefore shows that there must be significant HI reservoirs in the circum-galactic medium and reinforces the idea that Lyα haloes are ubiquitous around high-redshift Lyα emitting galaxies. Our characterization of the Lyα haloes indicates that the majority of the Lyα flux comes from the halo (≈65%) and that their scale lengths seem to be linked to the UV properties of the galaxies (sizes and magnitudes). We do not observe a significant Lyα halo size evolution with redshift, although our sample for z> 5 is very small. We also explore the diversity of the Lyα line profiles in our sample and we find that the Lyα lines cover a large range of full width at half maximum (FWHM) from 118 to 512 km s<SUP>-1</SUP>. While the FWHM does not seem to be correlated to the Lyα scale length, most compact Lyα haloes and those that are not detected with high significance tend to have narrower Lyα profiles (<350 km s<SUP>-1</SUP>). Finally, we investigate the origin of the extended Lyα emission but we conclude that our data do not allow us to disentangle the possible processes, i.e. scattering from star-forming regions, fluorescence, cooling radiation from cold gas accretion, and emission from satellite galaxies. MUSE Ultra Deep Field Lyα haloes catalog (Table B.1) is also available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A8">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A8</A>...

We provide, for the first time, robust observational constraints on the galaxy major merger fraction up to z ≈ 6 using spectroscopic close pair counts. Deep Multi Unit Spectroscopic Explorer (MUSE) observations in the Hubble Ultra Deep Field (HUDF) and Hubble Deep Field South (HDF-S) are used to identify 113 secure close pairs of galaxies among a parent sample of 1801 galaxies spread over a large redshift range (0.2 < z < 6) and stellar masses (10<SUP>7</SUP>-10<SUP>11</SUP> M<SUB>☉</SUB>), thus probing about 12 Gyr of galaxy evolution. Stellar masses are estimated from spectral energy distribution (SED) fitting over the extensive UV-to-NIR HST photometry available in these deep Hubble fields, adding Spitzer IRAC bands to better constrain masses for high-redshift (z ⩾ 3) galaxies. These stellar masses are used to isolate a sample of 54 major close pairs with a galaxy mass ratio limit of 1

We present the deepest study to date of the Lyα luminosity function in a blank field using blind integral field spectroscopy from MUSE. We constructed a sample of 604 Lyα emitters (LAEs) across the redshift range 2.91 < z < 6.64 using automatic detection software in the Hubble Ultra Deep Field. The deep data cubes allowed us to calculate accurate total Lyα fluxes capturing low surface-brightness extended Lyα emission now known to be a generic property of high-redshift star-forming galaxies. We simulated realistic extended LAEs to fully characterise the selection function of our samples, and performed flux-recovery experiments to test and correct for bias in our determination of total Lyα fluxes. We find that an accurate completeness correction accounting for extended emission reveals a very steep faint-end slope of the luminosity function, α, down to luminosities of log<SUB>10</SUB>L erg s<SUP>-1</SUP>< 41.5, applying both the 1 /V<SUB>max</SUB> and maximum likelihood estimators. Splitting the sample into three broad redshift bins, we see the faint-end slope increasing from -2.03<SUB>-0.07</SUB><SUP>+ 1.42</SUP> at z ≈ 3.44 to -2.86<SUB>-∞</SUB><SUP>+0.76</SUP> at z ≈ 5.48, however no strong evolution is seen between the 68% confidence regions in L<SUP>∗</SUP>-α parameter space. Using the Lyα line flux as a proxy for star formation activity, and integrating the observed luminosity functions, we find that LAEs' contribution to the cosmic star formation rate density rises with redshift until it is comparable to that from continuum-selected samples by z ≈ 6. This implies that LAEs may contribute more to the star-formation activity of the early Universe than previously thought, as any additional intergalactic medium (IGM) correction would act to further boost the Lyα luminosities. Finally, assuming fiducial values for the escape of Lyα and LyC radiation, and the clumpiness of the IGM, we integrated the maximum likelihood luminosity function at 5.00 <z< 6.64 and find we require only a small extrapolation beyond the data (< 1 dex in luminosity) for LAEs alone to maintain an ionised IGM at z ≈ 6.... / We present the deepest study to date of the Ly alpha luminosity function in a blank field using blind integral field spectroscopy from MUSE. We constructed a sample of 604 Ly alpha emitters (LAEs) across the redshift range 2.91 < z < 6.64 using automatic detection software in the Hubble Ultra Deep Lield. The deep data cubes allowed us to calculate accurate total Ly alpha fluxes capturing low surface-brightness extended Ly alpha emission now known to be a generic property of high-redshift star-forming galaxies. We simulated realistic extended LAEs to fully characterise the selection function of our samples, and performed flux-recovery experiments to test and correct for bias in our determination of total Ly alpha fluxes. We find that an accurate completeness correction accounting for extended emission reveals a very steep faint-end slope of the luminosity function, alpha, down to luminosities of log(10) L erg s(-1) < 41.5, applying both the 1/V-max and maximum likelihood estimators. Splitting the sample into three broad redshift bins, we see the faint-end slope increasing from -2.03(-0.07)(+1.42) at z approximate to 3.44 to -2.86(-infinity)(+0.76) Z approximate to 76 at z approximate to 5.48, however no strong evolution is seen between the 68% confidence regions in L*-alpha parameter space. Using the Ly alpha line flux as a proxy for star formation activity, and integrating the observed luminosity functions, we find that LAEs' contribution to the cosmic star formation rate density rises with redshift until it is comparable to that from continuum-selected samples by z approximate to 6. This implies that LAEs may contribute more to the star-formation activity of the early Universe than previously thought, as any additional intergalactic medium (IGM) correction would act to further boost the Ly alpha luminosities. Linally, assuming fiducial values for the escape of Ly alpha and LyC radiation, and the dumpiness of the IGM, we integrated the maximum likelihood luminosity function at 5.00 < z < 6.64 and find we require only a small extrapolation beyond the data (<1 dex in luminosity) for LAEs alone to maintain an ionised IGM at z approximate to 6.

We tested the performance of photometric redshifts for galaxies in the Hubble Ultra Deep field down to 30th magnitude. We compared photometric redshift estimates from three spectral fitting codes from the literature (EAZY, BPZ and BEAGLE) to high quality redshifts for 1227 galaxies from the MUSE integral field spectrograph. All these codes can return photometric redshifts with bias |(z(MUSE) - pz)/(1 + z(MUSE))| < 0.05 down to F775W = 30 and spectroscopic incompleteness is unlikely to strongly modify this statement. We have, however, identified clear systematic biases in the determination of photometric redshifts

We present an analysis of [O I](63), [O III](88), [N II](122), and [C II](158) far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for similar to 240 local luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. We find pronounced declines ("deficits") of line-to-FIR continuum emission for [N II](122), [O I](63), and [C II](158) as a function of FIR color and infrared luminosity surface density, Sigma(IR). The median electron density of the ionized gas in LIRGs, based on the [N II](122)/[N II](205) ratio, is n(e) = 41 cm(-3). We find that the dispersion in the [C II](158) deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed [C II](158) emission, f ([C II](158)(PDR)) = [C II](158)(PDR)/C II](158), which increases from similar to 60% to similar to 95% in the warmest LIRGs. The [O I](63)/[C II](158)(PDR) ratio is tightly correlated with the PDR gas kinetic temperaturein sources where [O I] 63 is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, n(H), and intensity of the interstellar radiation field, G, in units of G(0) and find G/n(H) ratios of similar to 0.1-50 G(0) cm(3), with ULIRGs populating the upper end of the distribution. There is a relation between G/n(H) and Sigma(IR), showing a critical break at Sigma(IR)* similar or equal to 5 x 10(10) L-circle dot kpc(-2). Below Sigma(IR)*, G/n(H) remains constant, similar or equal to 0.32G(0) cm(3), and variations in Sigma(IR) are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. Above Sigma(IR)*, G/n(H) increases rapidly with Sigma(IR), signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.

Spectroscopic redshift measurements of the MUSE Hubble Ultra Deep Field Survey. File udf10. fit and mosaic.fit contain MUSE spectroscopic redshifts in the ultra-deep and deep fields, respectively. File combined.fit are the combined catalog of udf10.fit and mosaic.fit whose duplicates are removed because the two fields are overlapping. (3 data files)....

We present an initial result from the <SUP>12</SUP>CO (J = 1-0) survey of 79 galaxies in 62 local luminous and ultraluminous infrared galaxy (LIRG and ULIRG) systems obtained using the 45 m telescope at the Nobeyama Radio Observatory. This is a systematic <SUP>12</SUP>CO (J = 1-0) survey of the Great Observatories All-sky LIRGs Survey (GOALS) sample. The molecular gas mass of the sample is in the range 2.2× {10}<SUP>8</SUP>{--}7.0× {10}<SUP>9</SUP> {M}<SUB>☉ </SUB> within the central several kiloparsecs subtended by the 15<SUP>\prime\prime</SUP> beam. A method to estimate the size of a CO gas distribution is introduced, which is combined with the total CO flux in the literature. This method is applied to part of our sample, and we find that the median CO radius is 1-4 kpc. From the early stage to the late stage of mergers, we find that the CO size decreases while the median value of the molecular gas mass in the central several-kiloparsec region is constant. Our results statistically support a scenario where molecular gas inflows toward the central region from the outer disk to replenish gas consumed by starburst, and that such a process is common in merging LIRGs....

We present the results of a Hubble Space Telescope ACS/HRC FUV, ACS/WFC optical study into the cluster populations of a sample of 22 Luminous Infrared Galaxies in the Great Observatories All-Sky LIRG Survey. Through integrated broadband photometry, we have derived ages and masses for a total of 484 star clusters contained within these systems. This allows us to examine the properties of star clusters found in the extreme environments of LIRGs relative to lower luminosity star-forming galaxies in the local universe. We find that by adopting a Bruzual & Charlot simple stellar population model and Salpeter initial mass function, the age distribution of the clusters declines as dN/d tau = tau(-0.9+/-0.3), consistent with the age distribution derived for the Antennae Galaxies, and interpreted as evidence for rapid cluster disruption occurring in the strong tidal fields of merging galaxies. The large number of 10(6) M-circle dot young clusters identified in the sample also suggests that LIRGs are capable of producing more high-mass clusters than what is observed to date in any lower luminosity star-forming galaxy in the local universe. The observed cluster mass distribution of dN/dM = M-1.95+/-0.11 is consistent with the canonical -2 power law used to describe the underlying initial cluster mass function (ICMF) for a wide range of galactic environments. We interpret this as evidence against mass-dependent cluster disruption, which would flatten the observed CMF relative to the underlying ICMF distribution.

We present the results from Atacama Large Millimeter/submillimeter Array imaging in the [N II] 205μm fine-structure line (hereafter [N II]) and the underlying continuum of BRI 1202-0725, an interacting galaxy system at z = 4.7, consisting of a quasi-stellar object (QSO), a submillimeter galaxy (SMG), and two Lyα emitters, all within ̃25 kpc of the QSO. We detect the QSO and SMG in both [N II] and continuum. At the ̃1″ (or 6.6 kpc) resolution, both the QSO and SMG are resolved in [N II], with the de-convolved major axes of ̃9 and ̃14 kpc, respectively. In contrast, their continuum emissions are much more compact and unresolved even at an enhanced resolution of ̃0.″7. The ratio of the [N II] flux to the existing CO(7-6) flux is used to constrain the dust temperature (T <SUB>dust</SUB>) for a more accurate determination of the FIR luminosity L <SUB>FIR</SUB>. Our best estimated T <SUB>dust</SUB> equals 43 (±2) K for both galaxies (assuming an emissivity index β = 1.8). The resulting L <SUB>CO(7-6)</SUB>/L <SUB>FIR</SUB> ratios are statistically consistent with that of local luminous infrared galaxies, confirming that L <SUB>CO(7-6)</SUB> traces the star formation (SF) rate (SFR) in these galaxies. We estimate that the ongoing SF of the QSO (SMG) has an SFR of 5.1 (6.9) × 10<SUP>3</SUP> M <SUB>☉</SUB> yr<SUP>-1</SUP> (±30%) assuming Chabrier initial mass function, takes place within a diameter (at half maximum) of 1.3 (1.5) kpc, and will consume the existing 5 (5) × 10<SUP>11</SUP> M <SUB>☉</SUB> of molecular gas in 10 (7) × 10<SUP>7</SUP> years. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc....

Our sensitive ({σ }<SUB>{ { n</SUB> } }≈ 572 {nJy} { { beam } }<SUP>-1</SUP>), high-resolution (FWHM {θ }<SUB>1/2</SUB>=0\buildrel{\prime\prime}\over{.} 22≈ 2 {kpc} {at} z≳ 1), 10 GHz image covering a single Karl G. Jansky Very Large Array (VLA) primary beam (FWHM { { {\Theta } }}<SUB>1/2</SUB>≈ 4\buildrel{ \prime}\over{.} 25) in the GOODS-N field contains 32 sources with {S}<SUB>{ { p</SUB> } }≳ 2 μ {Jy} { { beam } }<SUP>-1</SUP> and optical and/or near-infrared (OIR) counterparts. Most are about as large as the star-forming regions that power them. Their median FWHM major axis is < {θ }<SUB>{ { M</SUB> } }> =167+/- 32 {mas}≈ 1.2+/- 0.28 {kpc}, with rms scatter ≈ 91 {mas}≈ 0.79 {kpc}. In units of the effective radius {r}<SUB>{ { e</SUB> } } that encloses half their flux, these radio sizes are < {r}<SUB>{ { e</SUB> } }> ≈ 69+/- 13 {mas}≈ 509+/- 114 {pc}, with rms scatter ≈ 38 {mas}≈ 324 {pc}. These sizes are smaller than those measured at lower radio frequencies, but agree with dust emission sizes measured at mm/sub-mm wavelengths and extinction-corrected Hα sizes. We made a low-resolution ({θ }<SUB>1/2</SUB>=1\buildrel{\prime\prime}\over{.} 0) image with ≈ 10× better brightness sensitivity, in order to detect extended sources and measure matched-resolution spectral indices {α }<SUB>1.4 {GHz</SUB>}<SUP>10 {GHz</SUP>}. It contains six new sources with {S}<SUB>{ { p</SUB> } }≳ 3.9 μ {Jy} { { beam } }<SUP>-1</SUP> and OIR counterparts. The median redshift of all 38 sources is < z> =1.24+/- 0.15. The 19 sources with 1.4 GHz counterparts have a median spectral index of < {α }<SUB>1.4 {GHz</SUB>}<SUP>10 {GHz</SUP>}> =-0.74+/- 0.10, with rms scatter ≈ 0.35. Including upper limits on α for sources not detected at 1.4 GHz flattens the median to < {α }<SUB>1.4 {GHz</SUB>}<SUP>10 {GHz</SUP>}> ≳ -0.61, suggesting that the μJy radio sources at higher redshifts—and hence those selected at higher rest-frame frequencies—may have flatter spectra. If the non-thermal spectral index is {α }<SUB>{NT</SUB>}≈ -0.85, the median thermal fraction of sources selected at median rest-frame frequency ≈ 20 {GHz} is ≳48%....

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The extragalactic background suggests half the energy generated by stars was reprocessed into the infrared (IR) by dust. At z ∼1.3, 90% of star formation is obscured by dust. To fully understand the cosmic star formation history, it is critical to investigate infrared emission. AKARI has made deep mid-IR observation using its continuous 9-band filters in the NEP field (5.4 deg^2), using ∼10% of the entire pointed observations available throughout its lifetime. However, there remain 11,000 AKARI infrared sources undetected with the previous CFHT/Megacam imaging (r ∼25.9ABmag). Redshift and IR luminosity of these sources are unknown. These sources may contribute significantly to the cosmic star-formation rate density (CSFRD). For example, if they all lie at 1 < z < 2, the CSFRD will be twice as high at the epoch. We are carrying out deep imaging of the NEP field in 5 broad bands (g,r,i,z, and y) using Hyper Suprime-Camera (HSC), which has 1.5 deg field of view in diameter on Subaru 8m telescope. This will provide photometric redshift information, and thereby IR luminosity for the previously-undetected 11,000 faint AKARI IR sources. Combined with AKARI's mid-IR AGN/SF diagnosis, and accurate mid-IR luminosity measurement, this will allow a complete census of cosmic star-formation/AGN accretion history obscured by dust....

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We report the detection of diffuse Lyα emission, or Lyα halos (LAHs), around star-forming galaxies at z ≈ 3.78 and 2.66 in the NOAO Deep Wide-Field Survey Boötes field. Our samples consist of a total of ̃1400 galaxies, within two separate regions containing spectroscopically confirmed galaxy overdensities. They provide a unique opportunity to investigate how the LAH characteristics vary with host galaxy large-scale environment and physical properties. We stack Lyα images of different samples defined by these properties and measure their median LAH sizes by decomposing the stacked Lyα radial profile into a compact galaxy-like and an extended halo-like component. We find that the exponential scale-length of LAHs depends on UV continuum and Lyα luminosities, but not on Lyα equivalent widths or galaxy overdensity parameters. The full samples, which are dominated by low UV-continuum luminosity Lyα emitters (M <SUB>UV</SUB> ≳ -21), exhibit LAH sizes of 5-6 kpc. However, the most UV- or Lyα-luminous galaxies have more extended halos with scale-lengths of 7-9 kpc. The stacked Lyα radial profiles decline more steeply than recent theoretical predictions that include the contributions from gravitational cooling of infalling gas and from low-level star formation in satellites. However, the LAH extent matches what one would expect for photons produced in the galaxy and then resonantly scattered by gas in an outflowing envelope. The observed trends of LAH sizes with host galaxy properties suggest that the physical conditions of the circumgalactic medium (covering fraction, H I column density, and outflow velocity) change with halo mass and/or star formation rates....

The gas accretion and star-formation histories of galaxies like the Milky Way remain an outstanding problem in astrophysics. Observations show that 8 billion years ago, at redshifts z > 1, the progenitors to Milky Way-mass galaxies were forming stars 30 times faster than today and predicted to be rich in molecular gas, in contrast with low present-day gas fractions (<10%). Using ALMA Band 4 observations, we detected the molecular gas using the CO(J=3-2) emission (rest-frame 345.8 GHz) in a sample of galaxies at redshifts z=1.2-1.3, selected to have the stellar mass (Log M<SUB>*</SUB>/M<SUB>☉</SUB> =10.2) and star-formation rate (SFR = 20 M<SUB>☉ </SUB>yr<SUP>-1</SUP>) of the main progenitors of today's Milky Way-mass galaxies at this epoch. We show that with relatively short ALMA integrations, we now probe efficiently the CO luminosities of z > 1 star-forming galaxies a factor two lower than was possible previously. The CO emission from these galaxies reveals large molecular gas reservoirs, with a ratio of molecular-gas mass-to-stellar mass of ~100%, indicating most of the baryons are in cold gas, not stars. The ratio of the galaxies' total luminosity from star formation to CO luminosity corresponds to long gas-consumption timescales. Compared to local spiral galaxies, the star-formation efficiency, estimated from the ratio of total IR luminosity to CO emission, has remained nearly constant since redshift z=1.2, despite the order of magnitude decrease in gas fraction, consistent with results for more massive and more luminous galaxies at this epoch. This implies that the the physical processes that determine the rate at which gas cools to form stars in distant galaxies appear to be similar to that in local galaxies....

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The gas accretion and star formation histories of galaxies like the Milky Way remain an outstanding problem in astrophysics(1,2). Observations show that 8 billion years ago, the progenitors to Milky Way-mass galaxies were forming stars 30 times faster than today and were predicted to be rich in molecular gas(3), in contrast to the low present-day gas fractions (<10%)(4-6). Here we show the detection of molecular gas from the CO (J = 3-2) emission (rest-frame 345.8 GHz) in galaxies at redshifts z = 1.2-1.3, selected to have the stellar mass and star formation rate of the progenitors of today's Milky Way-mass galaxies. The CO emission reveals large molecular gas masses, comparable to or exceeding the galaxy stellar masses, and implying that most of the baryons are in cold gas, not stars. The total luminosities of the galaxies from star formation and CO luminosities yield long gas consumption timescales. Compared to local spiral galaxies, the star formation efficiency, estimated from the ratio of total infrared luminosity (L-IR) to CO emission, has remained nearly constant since redshift z = 1.2, despite the order of magnitude decrease in gas fraction, consistent with the results for other galaxies at this epoch(7-10). Therefore, the physical processes that determine the rate at which gas cools to form stars in distant galaxies appear to be similar to that in local galaxies.

We present the rationale for and the observational description of ASPECS

We present a search for [C II] line and dust continuum emission from optical dropout galaxies at z > 6 using ASPECS, our Atacama Large Millimeter submillimeter Array Spectroscopic Survey in the Hubble Ultra-deep Field (UDF). Our observations, which cover the frequency range of 212-272 GHz, encompass approximately the range of 6 < z < 8 for [C II] line emission and reach a limiting luminosity of L-[C II] similar to (1.6-2.5) x 10(8) L-circle dot.We identify 14 [C II] line emitting candidates in this redshift range with significances > 4.5 sigma, two of which correspond to blind detections with no optical counterparts. At this significance level, our statistical analysis shows that about 60% of our candidates are expected to be spurious. For one of our blindly selected [C II] line candidates, we tentatively detect the CO(6-5) line in our parallel 3 mm line scan. None of the line candidates are individually detected in the 1.2 mm continuum. A stack of all [C II] candidates results in a tentative detection with S-1.2 (mm) = 14 +/- 5 mu Jy. This implies a dust-obscured star-formation rate (SFR) of (3 +/- 1) M-circle dot yr(-1). We find that the two highest-SFR objects have candidate [C II] lines with luminosities that are consistent with the low-redshift L-[C II] versus SFR relation. The other candidates have significantly higher [C II] luminosities than expected from their UV-based SFR. At the current sensitivity, it is unclear whether the majority of these sources are intrinsically bright [C II] emitters, or spurious sources. If only one of our line candidates was real (a scenario greatly favored by our statistical analysis), we find a source density for [C II] emitters at 6 < z < 8 that is significantly higher than predicted by current models and some extrapolations from galaxies in the local universe.

We study the molecular gas properties of high-z galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets an similar to 1 arcmin(2) region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3 and 1 mm bands. Of a total of 1302 galaxies in the field, 56 have spectroscopic redshifts and correspondingly well-defined physical properties. Among these, 11 have infrared luminosities L-IR > 10(11) L-circle dot, i.e., a detection in CO emission was expected. Out of these, 7 are detected at various significance in CO, and 4 are undetected in CO emission. In the CO-detected sources, we find CO excitation conditions that are lower than those typically found in starburst/sub-mm galaxy/QSO environments. We use the CO luminosities (including limits for non-detections) to derive molecular gas masses. We discuss our findings in the context of previous molecular gas observations at high redshift (star formation law, gas depletion times, gas fractions)

We present an analysis of a deep (1 sigma = 13 mu Jy) cosmological 1.2 mm continuum map based on ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field. In the 1 arcmin(2) covered by ASPECS we detect nine sources at >3.5 sigma significance at 1.2 mm. Our ALMA-selected sample has a median redshift of z = 1.6 +/- 0.4, with only one galaxy detected at z > 2 within the survey area. This value is significantly lower than that found in millimeter samples selected at a higher flux density cut-off and similar frequencies. Most galaxies have specific star formation rates similar to that of main sequence galaxies at the same epoch, and we find median values of stellar mass and star formation rates of 4.0 x 10(10) M circle dot and similar to 40 M circle dot yr(-1), respectively. Using the dust emission as a tracer for the ISM mass, we derive depletion times that are typically longer than 300 Myr, and we find molecular gas fractions ranging from similar to 0.1 to 1.0. As noted by previous studies, these values are lower than using CO-based ISM estimates by a factor similar to 2. The 1\,mm number counts (corrected for fidelity and completeness) are in agreement with previous studies that were typically restricted to brighter sources. With our individual detections only, we recover 55% +/- 4% of the extragalactic background light (EBL) at 1.2 mm measured by the Planck satellite, and we recover 80% +/- 7% of this EBL if we include the bright end of the number counts and additional detections from stacking. The stacked contribution is dominated by galaxies at z similar to 1-2, with stellar masses of (1-3) x 10(10) M circle dot. For the first time, we are able to characterize the population of galaxies that dominate the EBL at 1.2 mm.

We used the MOSAIC1.1 camera at the f/3.1 prime focus of the 4m Mayall Telescope at the Kitt Peak National Observatory on U.T. 2014 April 24-29 to obtain deep narrow- and broadband imaging of a field just south of the region imaged by Lee et al. (2014ApJ...796..126L). The new field (central pointing of RA=14

<BR /> Aims

We present new observations of the field containing the z = 3.786 protocluster PC 217.96+32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1.°2 × 0.°6 area (≈150 × 75 comoving Mpc) surrounding the protocluster’s core and discovered 165 candidate Lyα emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (I.e., within a radius of 2.5 comoving Mpc) of 14 ± 7 relative to the average LAE spatial density (\bar{ρ }) in the imaged field. Further, \bar{ρ } is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 ± 0.010. The velocity dispersion of galaxies near the core is σ = 350 ± 40 km s<SUP>-1</SUP>, a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of >10<SUP>15</SUP> M <SUB>☉</SUB> and >6 × 10<SUP>14</SUP> M <SUB>☉</SUB>. The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Lyα) luminosity and environmental density

We present the first direct comparison between Balmer line and panchromatic spectral energy distribution (SED)-based star formation rates (SFRs) for z̃ 2 galaxies. For this comparison, we used 17 star-forming galaxies selected from the MOSFIRE Deep Evolution Field (MOSDEF) survey, with 3σ detections for Hα and at least two IR bands (Spitzer/MIPS 24 μm and Herschel/PACS 100 and 160 μm, and in some cases Herschel/SPIRE 250, 350, and 500 μm). The galaxies have total IR (8-1000 μm) luminosities of ̃ 10<SUP>11.4</SUP>-10<SUP>12.4</SUP> L<SUB>☉</SUB> and SFRs of ̃ 30-250 M<SUB>☉</SUB> yr<SUP>-1</SUP>. We fit the UV-to-far-IR SEDs with flexible stellar population synthesis (FSPS) models—which include both stellar and dust emission—and compare the inferred SFRs with the SFR(Hα, Hβ) values corrected for dust attenuation using Balmer decrements. The two SFRs agree with a scatter of 0.17 dex. Our results imply that the Balmer decrement accurately predicts the obscuration of the nebular lines and can be used to robustly calculate SFRs for star-forming galaxies at z̃ 2 with SFRs up to ̃ 200 M<SUB>☉</SUB> yr<SUP>-1</SUP>. We also use our data to assess SFR indicators based on modeling the UV-to-mid-IR SEDs or by adding SFR(UV) and SFR(IR), for which the latter is based on the mid-IR only or on the full IR SED. All these SFRs show a poorer agreement with SFR(Hα, Hβ) and in some cases large systematic biases are observed. Finally, we show that the SFR and dust attenuation derived from the UV-to-near-IR SED alone are unbiased when assuming a delayed exponentially declining star formation history. Based on observations made with the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration.... / We present the first direct comparison between Balmer line and panchromatic spectral energy distribution (SED)-based star formation rates (SFRs) for z similar to 2 galaxies. For this comparison, we used 17 star-forming galaxies selected from the MOSFIRE Deep Evolution Field (MOSDEF) survey, with 3 sigma detections for H alpha and at least two IR bands (Spitzer/MIPS 24 mu m and Herschel/PACS 100 and 160 mu m, and in some cases Herschel/SPIRE 250, 350, and 500 mu m). The galaxies have total IR (8-1000 mu m) luminosities of similar to 10(11.4)-10(12.4) L-circle dot and SFRs of similar to 30-250 M-circle dot yr(-1).. We fit the UV-to-far-IR SEDs with flexible stellar population synthesis (FSPS) models-which include both stellar and dust emission-and compare the inferred SFRs with the SFR(H alpha, H beta) values corrected for dust attenuation using Balmer decrements. The two SFRs agree with a scatter of 0.17 dex. Our results imply that the Balmer decrement accurately predicts the obscuration of the nebular lines and can be used to robustly calculate SFRs for star-forming galaxies at z similar to 2 with SFRs up to similar to 200 M-circle dot yr(-1).. We also use our data to assess SFR indicators based on modeling the UV-to-mid-IR SEDs or by adding SFR(UV) and SFR(IR), for which the latter is based on the mid-IR only or on the full IR SED. All these SFRs show a poorer agreement with SFR(H alpha, H beta) and in some cases large systematic biases are observed. Finally, we show that the SFR and dust attenuation derived from the UV-to-near-IR SED alone are unbiased when assuming a delayed exponentially declining star formation history.

In this paper, we report our high-resolution (0 ''.20 x 0 ''.14 or similar to 70 x 49 pc) observations of the CO(6-5) line emission, which probes warm and dense molecular gas, and the 434 mu m dust continuum in the nuclear region of NGC 7130, obtained with the Atacama Large Millimeter Array (ALMA). The CO line and dust continuum fluxes detected in our ALMA observations are 1230 +/- 74 Jy km s(-1) and 814 +/- 52 mJy, respectively, which account for 100% and 51% of their total fluxes. We find that the CO(6-5) and dust emissions are generally spatially correlated, but their brightest peaks show an offset of similar to 70 pc, suggesting that the gas and dust emissions may start decoupling at this physical scale. The brightest peak of the CO(6-5) emission does not spatially correspond to the radio continuum peak, which is likely dominated by an active galactic nucleus (AGN). This, together with our additional quantitative analysis, suggests that the heating contribution of the AGN to the CO(6-5) emission in NGC 7130 is negligible. The CO(6-5) and the extinction-corrected Pa-alpha maps display striking differences, suggestive of either a breakdown of the correlation between warm dense gas and star formation at linear scales of <100 pc or a large uncertainty in our extinction correction to the observed Pa-a image. Over a larger scale of similar to 2.1 kpc, the doublelobed structure found in the CO(6-5) emission agrees well with the dust lanes in the optical/near-infrared images.

The FourStar Galaxy Evolution Survey (ZFOURGE

We build a set of composite galaxy spectral energy distributions (SEDs) by de-redshifting and scaling multi-wavelength photometry from galaxies in the ZFOURGE survey, covering the CDFS, COSMOS, and UDS fields. From a sample of similar to 4000 K-s-band selected galaxies, we define 38 composite galaxy SEDs that yield continuous low-resolution spectra (R similar to 45) over the rest-frame range 0.1-4 mu m. Additionally, we include far infrared photometry from the Spitzer Space Telescope and the Herschel Space Observatory to characterize the infrared properties of our diverse set of composite SEDs. From these composite SEDs we analyze the rest-frame UVJ colors, as well as the ratio of IR to UV light (IRX) and the UV slope (beta) in the IRX-beta dust relation at 1 < z < 3. Blue star-forming composite SEDs show IRX and beta values consistent with local relations; dusty star-forming galaxies have considerable scatter, as found for local IR bright sources, but on average appear bluer than expected for their IR fluxes. We measure a tight linear relation between rest-frame UVJ colors and dust attenuation for star-forming composites, providing a direct method for estimating dust content from either (U - V) or (V - J) rest-frame colors for star-forming galaxies at intermediate redshifts.

We explore star formation histories (SFHs) of galaxies based on the evolution of the star formation rate stellar mass relation (SFR-M-*). Using data from the FourStar Galaxy Evolution Survey (ZFOURGE) in combination with far-IR imaging from the Spitzer and Herschel observatories we measure the SFR-M-* relation at 0.5 < z < 4. Similar to recent works we find that the average infrared spectral energy distributions of galaxies are roughly consistent with a single infrared template across a broad range of redshifts and stellar masses, with evidence for only weak deviations. We find that the SFR-M-* relation is not consistent with a single power law of the form SFR proportional to M-*(alpha) at any redshift; it has a power law slope of alpha similar to 1 at low masses, and becomes shallower above a turnover mass (M-0) that ranges from 10(9.5) to 10(10.8) M-circle dot, with evidence that M-0 increases with redshift. We compare our measurements to results from state-of-the-art cosmological simulations, and find general agreement in the slope of the SFR-M-* relation albeit with systematic offsets. We use the evolving SFR-M-* sequence to generate SFHs, finding that typical SFRs of individual galaxies rise at early times and decline after reaching a peak. This peak occurs earlier for more massive galaxies. We integrate these SFHs to generate mass growth histories and compare to the implied mass growth from the evolution of the stellar mass function (SMF). We find that these two estimates are in broad qualitative agreement, but that there is room for improvement at a more detailed level. At early times the SFHs suggest mass growth rates that are as much as 10x higher than inferred from the SMF. However, at later times the SFHs under-predict the inferred evolution, as is expected in the case of additional growth due to mergers.

We have undertaken an ambitious program to visually classify all galaxies in the five CANDELS fields down to H < 24.5 involving the dedicated efforts of over 65 individual classifiers. Once completed, we expect to have detailed morphological classifications for over 50,000 galaxies spanning 0 < z < 4 over all the fields, with classifications from 3 to 5 independent classifiers for each galaxy. Here, we present our detailed visual classification scheme, which was designed to cover a wide range of CANDELS science goals. This scheme includes the basic Hubble sequence types, but also includes a detailed look at mergers and interactions, the clumpiness of galaxies, k-corrections, and a variety of other structural properties. In this paper, we focus on the first field to be completed-GOODS-S, which has been classified at various depths. The wide area coverage spanning the full field (wide+deep+ERS) includes 7634 galaxies that have been classified by at least three different people. In the deep area of the field, 2534 galaxies have been classified by at least five different people at three different depths. With this paper, we release to the public all of the visual classifications in GOODS-S along with the Perl/Tk GUI that we developed to classify galaxies. We present our initial results here, including an analysis of our internal consistency and comparisons among multiple classifiers as well as a comparison to the Sersic index. We find that the level of agreement among classifiers is quite good (>70% across the full magnitude range) and depends on both the galaxy magnitude and the galaxy type, with disks showing the highest level of agreement (>50%) and irregulars the lowest (<10%). A comparison of our classifications with the Sersic index and rest-frame colors shows a clear separation between disk and spheroid populations. Finally, we explore morphological k-corrections between the V-band and H-band observations and find that a small fraction (84 galaxies in total) are classified as being very different between these two bands. These galaxies typically have very clumpy and extended morphology or are very faint in the V-band.

We present new Institut de Radioastronomie Millimetrique (TRAM) 30 m spectroscopic observations of the similar to 88 GHz band, including emission from the CCH (N = 1 -> 0) multiplet, HCN (J = 1 -> 0), HCO (J = 1 -> 0), and HNC (J = 1 -> 0), for a sample of 58 local luminous and ultraluminous infrared galaxies from the Great Observatories All-sky LIRG Survey (GOALS). By combining our new TRAM data with literature data and Spitzer /IRS spectroscopy, we study the correspondence between these putative tracers of dense gas and the relative contribution of active galactic nuclei (AGNs) and star formation to the mid-infrared luminosity of each system. We find the HCN (1-0) emission to be enhanced in AGN-dominated systems (L'(HCN(1 0))/ L'(HCO+(1-o))) = 1.84), compared to composite and starburst-dominated systems (L'HCN(1413/(1-0)) = 1.14, and 0.88, respectively). However, some composite and starburst systems have LH/ CN (1 0) /LH/ CO (1 0) ratios comparable to those of AGNs, indicating that enhanced HCN emission is not uniquely associated with energetically dominant AGNs. After removing AGN-dominated systems from the sample, we find a linear relationship (within the uncertainties) between logio(L'(HCN(1-0))) and log(10)(LIR), consistent with most previous findings. Lc N(1 0) /LIR, typically interpreted as the dense-gas depletion time, appears to have no systematic trend with LIR for our sample of luminous and ultraluminous infrared galaxies, and has significant scatter. The galaxyintegrated L'(HCN(1-0)) and L'(HCO+(1-0)) emission do not appear to have a simple interpretation in terms of the AGN dominance or the star formation rate, and are likely determined by multiple processes, including density and radiative effects.

We present the photometric properties of a sample of infrared (IR) bright dust-obscured galaxies (DOGs). Combining wide and deep optical images obtained with the Hyper Suprime-Cam on the Subaru Telescope and all-skymid-IR (MIR) images taken with Wide-Field Infrared Survey Explorer, we discovered 48 DOGs with i-K-s > 1.2 and i-[22] > 7.0, where i, K-s, and [22] represent AB magnitude in the i-band, K-s-band, and 22 mu m, respectively, in the GAMA 14 hr field (similar to 9 deg(2)). Among these objects, 31 (similar to 65%) show power-law spectral energy distributions (SEDs) in the near-IR (NIR) and MIR regime, while the remainder show an NIR bump in their SEDs. Assuming that the redshift distribution for our DOGs sample is Gaussian, with mean and sigma z = 1.99 +/- 0.45, we calculated their total IR luminosity using an empirical relation between 22 mu m luminosity and total IR luminosity. The average value of the total IR luminosity is (3.5 +/- 1.1) x 10(13) L circle dot, which classifies them as hyper-luminous infrared galaxies. We also derived the total IR luminosity function (LF) and IR luminosity density (LD) for a flux-limited subsample of 18 DOGs with 22 mu m flux greater than 3.0 mJy and with i-band magnitude brighter than 24 AB magnitude. The derived space density for this subsample is log phi = -6.59 +/- 0.11 [Mpc(-3)]. The IR LF for DOGs including data obtained from the literature is fitted well by a double-power law. The derived lower limit for the IR LD for our sample is rho(IR) similar to 3.8 x 10(7) [L circle dot Mpc(-3]) and its contributions to the total IR LD, IR LD of all ultra-luminous infrared galaxies, and that of all DOGs are > 3%, > 9%, and > 15%, respectively.

One of the candidate carries of the UV bump is polycyclic aromatic hydrocarbon (PAH) which can be detected in the infrared. Its flux ratios are expected to correlate with the strength or width of the UV bump. We propose to use the LRIS spectroscopy to observe the UV bump in 11 z 1 star-forming galaxies in the GOODS-South field, for which we have Spitzer mid-infrared spectra. With the LRIS spectra, we will compare the profile and strength of the UV bump with the PAH flux ratios to establish the relationship between the UV bump and the PAH dust features....

Galaxy formation and evolution studies rely on the robust determination of galaxy properties such as stellar masses and star formation rates (SFR). One the one hand these are important to distinguish between star bursting galaxies, normally star forming galaxies and those in the process of quenching and reveal the underlying processes causing these phenomena. On the other hand, they are crucial to derive reliable estimates of global properties like the star formation rate density of the Universe and the stellar mass assembly. We exploit the excellent multi-wavelength data in the GOODS-S, GOODS-N, UDS and COSMOS CANDELS fields ranging from deep ground and space-based optical data, deep-NIR HST data from CANDELS to the deepest FIR PACS data available from CANDELS-Herschel and Pep/GOODS-Herschel to estimate SFRs of IR-luminous galaxies between redshift 1 and 2. We determine SFRs in three different ways

Cold molecular gas and star formation in local Luminous Infrared Galaxies (LIRGs) are studied along the stage of the galaxy merger sequence. Most local LIRGs are starbursting and are involved with galaxy-galaxy interactions or mergers. The evolution and the direct trigger of the merger-driven starbursts are not clear observationally, although there are several theoretical explanations. In order to address these issues, information of the molecular gas, which is traced by a <SUP>12</SUP>CO(J=1-0) emission line, of an unbiased LIRG sample is required. To this end, a CO survey of 79 galaxies in 62 LIRG systems were conducted with the Nobeyama 45 m telescope. A method is developed to estimate the extent of CO gas in galaxies using combinations of two single-aperture telescopes with different beam sizes. The majority of the sources have the CO radius of less than ~ 4 kpc. The CO extent is found to possibly decrease from the early stage to the late stage of the merger. The molecular gas mass in the central several kilo-parsecs is constant throughout the merger sequence. These results statistically support a theoretically predicted scenario where the global gas inflow towards the galaxy center is common in merging LIRGs. The star formation efficiencies (SFE) in the central regions are derived and are high compared to disk star-forming galaxies as is well known. The SFE are found to be fairly independent of the merger stage. The star formation of merging LIRGs may be controlled by a common relation from gas to stars regardless of the merger stage, where SFR and resultant IR luminosity are determined by the amount of the molecular gas supplied by global inflow....

We will present new IRAM 30m observations of the HCN (1-0) and HCO+ (1-0) emission in a sample of Luminous and Ultraluminous Infrared Galaxies from the Great Observatories All-sky LIRG Survey. These new measurements are compared with mid-infrared AGN diagnostics to ascertain if enhanced HCN emission (relative to HCO+) correlates with increased AGN dominance. I will also compare consider the global relationships of these dense gas tracers with the infrared luminosity, to investigate the relationship between the HCN and HCO+ luminosities and the ongoing star formation. These comparisons suggest the HCN and HCO+ emission depend on both density and radiative effects (XDRs, mid-infrared pumping), obstructing a simple interpretation of the HCN/HCO+ ratio....

Do spatial distributions of dust grains in galaxies have typical forms, as do spatial distributions of stars? We investigate whether or not the distributions resemble uniform foreground screens, as commonly assumed by the high-redshift galaxy community. We use rest-frame infrared, ultraviolet, and H$\alpha$ line luminosities of dust-poor and dusty galaxies at z ~ 0 and z ~ 1 to compare measured H$\alpha$ escape fractions with those predicted by the Calzetti attenuation formula. The predictions, based on UV escape fractions, overestimate the measured H$\alpha$ escape fractions for all samples. The interpretation of this result for dust-poor z ~ 0 galaxies is that regions with ionizing stars have more dust than regions with nonionizing UV-emitting stars. Dust distributions for these galaxies are nonuniform. The interpretation of the overestimates for dusty galaxies at both redshifts is less clear. If the attenuation formula is inapplicable to these galaxies, perhaps the disagreements are unphysical; perhaps dust distributions in these galaxies are uniform. If the attenuation formula does apply, then dusty galaxies have nonuniform dust distributions; the distributions are more uniform than they are in dust-poor galaxies. A broad range of H$\alpha$ escape fractions at a given UV escape fraction for z ~ 1 dusty galaxies, if real, indicates diverse dust morphologies and the implausibility of the screen assumption....

Galaxies with stellar masses near M* contain the majority of stellar mass in the universe, and are therefore of special interest in the study of galaxy evolution. The Milky Way (MW) and Andromeda (M31) have present-day stellar masses near M*, at 5 x 10(10) M-circle dot (defined here to be MW-mass) and 10(11) M-circle dot (defined to be M31-mass). We study the typical progenitors of these galaxies using the FOURSTAR Galaxy Evolution Survey (ZFOURGE). ZFOURGE is a deep medium-band near-IR imaging survey, which is sensitive to the progenitors of these galaxies out to z similar to 3. We use abundance-matching techniques to identify the main progenitors of these galaxies at higher redshifts. We measure the evolution in the stellar mass, rest-frame colors, morphologies, far-IR luminosities, and star formation rates, combining our deep multiwavelength imaging with near-IR Hubble Space Telescope imaging from Cosmic Near-IR Deep Extragalactic Legacy Survey (CANDELS), and Spitzer and Herschel far-IR imaging from Great Observatories Origins Deep Survey-Herschel and CANDELS-Herschel. The typical MW-mass and M31-mass progenitors passed through the same evolution stages, evolving from blue, star-forming disk galaxies at the earliest stages to redder dust-obscured IR-luminous galaxies in intermediate stages and to red, more quiescent galaxies at their latest stages. The progenitors of the MW-mass galaxies reached each evolutionary stage at later times (lower redshifts) and with stellar masses that are a factor of two to three lower than the progenitors of the M31-mass galaxies. The process driving this evolution, including the suppression of star formation in present-day M* galaxies, requires an evolving stellar-mass/halo-mass ratio and/or evolving halo-mass threshold for quiescent galaxies. The effective size and SFRs imply that the baryonic cold-gas fractions drop as galaxies evolve from high redshift to z similar to 0 and are strongly anticorrelated with an increase in the Sersic index. Therefore, the growth of galaxy bulges in M* galaxies corresponds to a rapid decline in the galaxy gas fractions and/or a decrease in the star formation efficiency.

To better characterize the global star formation activity in a galaxy, one needs to know not only the star formation rate (SFR) but also the rest-frame, far-infrared color (e.g., the 60-100 μm color, C(60/100)) of the dust emission. The latter probes the average intensity of the dust heating radiation field and scales statistically with the effective SFR surface density in star-forming galaxies including (ultra-)luminous infrared galaxies ((U)LIRGs). To this end, here we exploit a new spectroscopic approach involving only two emission lines

We present an analysis of the deepest Herschel images in four major extragalactic fields GOODS-North, GOODS-South, UDS, and COSMOS obtained within the GOODS-Herschel and CANDELS-Herschel key programs. The star formation picture provided by a total of 10 497 individual far-infrared detections is supplemented by the stacking analysis of a mass complete sample of 62 361 star-forming galaxies from the Hubble Space Telescope (HST) H band-selected catalogs of the CANDELS survey and from two deep ground-based K-8 band-selected catalogs in the GOODS-North and the COSMOS-wide field to obtain one of the most accurate and unbiased understanding to date of the stellar mass growth over the cosmic history. We show, for the first time, that stacking also provides a powerful tool to determine the dispersion of a physical correlation and describe our method called "scatter stacking", which may be easily generalized to other experiments. The combination of direct UV and far-infrared UV-reprocessed light provides a complete census on the star formation rates (SFRs), allowing us to demonstrate that galaxies at z = 4 to 0 of all stellar masses (M-*) follow a universal scaling law, the so-called main sequence of star-forming galaxies. We find a universal close-to-linear slope of the log(10)(SFR)-log(10)(M-*) relation, with evidence for a flattening of the main sequence at high masses (log(10)(M-*/M-circle dot) > 10.5) that becomes less prominent with increasing redshift and almost vanishes by z similar or equal to 2. This flattening may be due to the parallel stellar growth of quiescent bulges in star-forming galaxies, which mostly happens over the same redshift range. Within the main sequence, we measure a nonvarying SFR dispersion of 0.3 dex

We present ALMA Cycle-0 observations of the CO (6-5) line emission and of the 435 μm dust continuum emission in the central kiloparsec of NGC 1614, a local luminous infrared galaxy at a distance of 67.8 Mpc (1{<SUP>\prime \prime </SUP>}= 329 pc). The CO emission is well resolved by the ALMA beam (0.''26 × 0.''20) into a circumnuclear ring, with an integrated flux of f <SUB> CO(6-5)</SUB> = 898 (± 153) Jy km s<SUP>-1</SUP>, which is 63(± 12)% of the total CO (6-5) flux measured by Herschel. The molecular ring, located between 100 pc < r < 350 pc from the nucleus, looks clumpy and includes seven unresolved (or marginally resolved) knots with median velocity dispersion of ~40 km s<SUP>-1</SUP>. These knots are associated with strong star formation regions with Σ<SUB>SFR</SUB> ~ 100 M <SUB>☉</SUB> yr<SUP>-1</SUP> kpc<SUP>-2</SUP> and Σ <SUB>Gas</SUB>̃ 10<SUP>4</SUP> {M}_☉ pc<SUP>-2</SUP>. The non-detections of the nucleus in both the CO (6-5) line emission and the 435 μm continuum rule out, with relatively high confidence, a Compton-thick active galactic nucleus in NGC 1614. Comparisons with radio continuum emission show a strong deviation from an expected local correlation between Σ<SUB>Gas</SUB> and Σ<SUB>SFR</SUB>, indicating a breakdown of the Kennicutt-Schmidt law on the linear scale of ~100 pc. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.... / We present ALMA Cycle-0 observations of the CO (6-5) line emission and of the 435 mu m dust continuum emission in the central kiloparsec of NGC 1614, a local luminous infrared galaxy at a distance of 67.8 Mpc (1 '' = 329 pc). The CO emission is well resolved by the ALMA beam (0.'' 26x0.'' 20) into a circumnuclear ring, with an integrated flux of f(C O(6-5)) = 898 (+/- 153) Jy km s(-1), which is 63(+/- 12)% of the total CO (6-5) flux measured by Herschel. The molecular ring, located between 100 pc < r < 350 pc from the nucleus, looks clumpy and includes seven unresolved (or marginally resolved) knots with median velocity dispersion of similar to 40 km s(-1). These knots are associated with strong star formation regions with Sigma(SFR) similar to 100M(circle dot) yr(-1) kpc(-2) and Sigma(Gas) similar to 10(4) M-circle dot pc(-2). The nondetections of the nucleus in both the CO (6-5) line emission and the 435 mu m continuum rule out, with relatively high confidence, a Compton-thick active galactic nucleus in NGC 1614. Comparisons with radio continuum emission show a strong deviation from an expected local correlation between Sigma(Gas) and Sigma(SFR), indicating a breakdown of the Kennicutt-Schmidt law on the linear scale of similar to 100 pc.

We report on measurements for dust extinction and star formation rates (SFRs) for luminous infrared galaxies (LIRGs). We utilized the hydrogen recombination lines Brα, Hα, and Hβ observed in the infrared and optical wavelengths with AKARI and the Lick Observatory's Kast Double spectrograph to produce spectra. By calculating Brα/Hα ratios for the target galaxies, extinction is estimated. A possible correlation between higher L<SUB>IR</SUB>, IR/UV, specific SFRs and higher Brα/Hα has been found. Through comparisons with Hα/Hβ, it may be possible to determine if Hα is, in fact, underestimating extinction, since Hα is more strongly affected by extinction compared to longer wavelengths such as Brα. The accuracy of using Hα in extinction corrections is important for SFR studies, and, thus, one goal is to find a more accurate reddening correction factor. Payne was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829)....

We present a new technique for overcoming confusion noise in deep far-infrared Herschel space telescope images making use of prior information from shorter lambda < 2 mu m wavelengths. For the deepest images obtained by Herschel, the flux limit due to source confusion is about a factor of three brighter than the flux limit due to instrumental noise and (smooth) sky background. We have investigated the possibility of de-confusing simulated Herschel PACS 160 mu m images by using strong Bayesian priors on the positions and weak priors on the flux of sources. We find the blended sources and group them together and simultaneously fit their fluxes. We derive the posterior probability distribution function of fluxes subject to these priors through Monte Carlo Markov Chain (MCMC) sampling by fitting the image. Assuming we can predict the FIR flux of sources based on the ultraviolet-optical part of their SEDs to within an order of magnitude, the simulations show that we can obtain reliable fluxes and uncertainties at least a factor of three fainter than the confusion noise limit of 3 sigma(c) = 2.7 mJy in our simulated PACS-160 image. This technique could in principle be used to mitigate the effects of source confusion in any situation where one has prior information of positions and plausible fluxes of blended sources. For Herschel, application of this technique will improve our ability to constrain the dust content in normal galaxies at high redshift.

The GOODS- and CANDELS-Herschel projects have taken the deepest FIR imaging in the GOODS-S, -N, COSMOS, and UDS fields. Taking advantage of Herschel measurements of the far-infrared dust emission peak to minimize uncertainties in the bolometric corrections, we are able to explore the evolution of dusty star formation via infrared luminosity functions. In addition, the multiple lines-of-sight of the very deep observations of the CANDELS fields let us average out the cosmic variance. Together with the HST-CANDELS data, we can correlate the far-infrared properties of both typical star-forming and starburst galaxies with other aspects such as unobscured star formation seen in the ultraviolet and optical, dust extinction, galaxy structure, stellar masses, obtained from the CANDELS multi-wavelength data and the high-resolution near-infrared imaging that only HST/WFC3 can provide....

We compare the morphologies of a sample of 20 luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS) in the FUV, B, I, and H bands, using the Gini (G) and M-20 parameters to quantitatively estimate the distribution and concentration of flux as a function of wavelength. Hubble Space Telescope (HST) images provide an average spatial resolution of similar to 80 pc. While our LIRGs can be reliably classified as mergers across the entire range of wavelengths studied here, there is a clear shift toward more negative M-20 (more bulge-dominated) and a less significant decrease in G values at longer wavelengths. We find no correlation between the derived FUV G-M-20 parameters and the global measures of the IR to FUV flux ratio (IRX). Given the fine resolution in our HST data, this suggests either that the UV morphology and IRX are correlated on very small scales, or that the regions emitting the bulk of the IR emission emit almost no FUV light. We use our multi-wavelength data to simulate how merging LIRGs would appear from z similar to 0.5-3 in deep optical and near-infrared images such as the Hubble Ultra-Deep Field, and use these simulations to measure the G-M-20 at these redshifts. Our simulations indicate a noticeable decrease in G, which flattens at z >= 2 by as much as 40%, resulting in mis-classifying our LIRGs as disk-like, even in the rest-frame FUV. The higher redshift values of M-20 for the GOALS sources do not appear to change more than about 10% from the values at z similar to 0. The change in G-M-20 is caused by the surface brightness dimming of extended tidal features and asymmetries, and also the decreased spatial resolution which reduced the number of individual clumps identified. This effect, seen as early as z similar to 0.5, could easily lead to an underestimate of the number of merging galaxies at high-redshift in the rest-frame FUV.

We report the discovery of a large-scale structure containing multiple protoclusters at z = 3.78 in the Bootes field. The spectroscopic discovery of five galaxies at z = 3.783 +/- 0.002 lying within 1Mpc of one another led us to undertake a deep narrow- and broadband imaging survey of the surrounding field. Within a comoving volume of 72 x 72 x 25 Mpc(3), we have identified 65 Ly alpha emitter (LAE) candidates at z = 3.795 +/- 0.015, and four additional galaxies at z(spec) = 3.730, 3.753, 3.780, 3.835. The galaxy distribution within the field is highly nonuniform, exhibiting three large (approximate to 3-5x) overdensities separated by 8-14 Mpc (physical) and possibly connected by filamentary structures traced by LAEs. The observed number of LAEs in the entire field is nearly twice the average expected in field environments based on estimates of the Lya luminosity function at these redshifts. We estimate that by z = 0 the largest overdensity will grow into a cluster of mass approximate to 10(15) M-circle dot; the two smaller overdensities will grow into clusters of mass (2-6) x 10(14)M(circle dot). The highest concentration of galaxies is located at the southern end of the image, suggesting that the current imaging may not map the true extent of the large-scale structure. Finding three large protocluster candidates within a single 0.3 deg(2) field is highly unusual; expectations from theory suggest that such alignments should occur less than 2% of the time. Searching for and characterizing such structures and accurately measuring their volume space density can therefore place constraints on the theory of structure formation. Such regions can also serve as laboratories for the study of galaxy formation in dense environments.

The combination of deep near-IR and optical HST imaging, deep Herschel photometry and vast amounts of ancillary data available highlight the CANDELS fields as the best photometrically observed areas in the sky. However, relative to the GOODS fields, the CANDELS-UDS lacks spectroscopic coverage, in particular of the Herschel-detected galaxies. By contrast, each of the GOODS fields (each 0.044 deg^2) has 3000-4000 published redshifts. We propose to rectify this with a GEMINI/GMOS spectroscopic survey on ~300 Herschel-selected galaxies in the CANDELS UDS field and increase the pool of galaxies with CANDELS HST+Herschel imaging that are observable with ALMA by a factor of 2. This proposal complements our 2014A (band 1) program of spectroscopy for Herschel sources in the CANDELS COSMOS field. Redshifts and spectral measurements will enhance the legacy value of the deepest HST + Herschel data, and will also allow us to study environmental effects as well as to address fundamental questions about what controls star formation in the majority of star-forming galaxies, including occasional boosting, quenching, and effects on the ISM....

The Great Observatories All-sky LIRG Survey (GOALS) is a comprehensive, multiwavelength study of luminous infrared galaxies (LIRGs) in the local universe. Here, we present the results of a multi-component, spectral decomposition analysis of the low-resolution mid-infrared (MIR) Spitzer Infrared Spectrograph spectra from 5-38 mu m of 244 LIRG nuclei. The detailed fits and high-quality spectra allow for characterization of the individual polycyclic aromatic hydrocarbon (PAH) features, warm molecular hydrogen emission, and optical depths for both silicate dust grains and water ices. We find that starbursting LIRGs, which make up the majority of the GOALS sample, are very consistent in their MIR properties (i.e., tau(9.7) mu m, tau(ice), neon line ratios, and PAH feature ratios). However, as their EQW(6.2 mu m) decreases, usually an indicator of an increasingly dominant active galactic nucleus (AGN), LIRGs cover a larger spread in these MIR parameters. The contribution from PAH emission to the total IR luminosity (L(PAH)/L(IR)) in LIRGs varies from 2%-29% and LIRGs prior to their first encounter show significantly higher L(PAH)/L(IR) ratios on average. We observe a correlation between the strength of the starburst (represented by IR8 = L-IR/L-8 mu m) and the PAH fraction at 8 mu m but no obvious link between IR8 and the 7.7 to 11.3 PAH ratio, suggesting that the fractional photodissociation region (PDR) emission, and not the overall grain properties, is associated with the rise in IR8 for galaxies off the starburst main sequence. We detect crystalline silicate features in similar to 6% of the sample but only in the most obscure sources (s(9.7 mu m) < -1.24). Ice absorption features are observed in similar to 11% (56%) of GOALS LIRGs (ULIRGs) in sources with a range of silicate depths. Most GOALS LIRGs have L(H-2)/L(PAH) ratios elevated above those observed for normal star-forming galaxies and exhibit a trend for increasing L(H-2)/L(PAH) ratio with increasing L(H-2). While star formation appears to be the dominant process responsible for exciting the H-2 in most of the GOALS galaxies, a subset of LIRGs (similar to 10%) shows excess H-2 emission that is inconsistent with PDR models and may be excited by shocks or AGN-induced outflows.

The dust-penetrating power of infrared observations will allow us to reveal the physical and chemical properties in and around the dust enshrouded nuclei of galaxies. While current near-infrared spectroscopic observations with 8-10m class telescopes can access to z=1-3 regime, they are still very challenging and limited to luminous targets. For z=0 objects, these telescopes can resolve HII regions, but we still do not fully understand the properties of more extreme star formation environments (e.g., rich in gas), which are more prevalent at higher redshifts. Near- and mid-infrared TMT instruments (e.g., two of the first light instruments IRIS and IRMS, and a planned mid-infrared instrument MICHI) will exploit TMT's unprecedented high spatial resolution to constrain the physical processes in individual dusty, intense star-forming regions of local galaxies as well as obtain resolved spectra for z=2-3 star-forming galaxies. During the era of 2020, JWST and SPICA are also expected to be commissioned. The high sensitivity of these space-based infrared observatories will facilitate investigations of the properties of dusty galaxies at even higher redshifts (z > 3). Only with the combination of ground- and space-observatories, we will be able to obtain a complete picture of star formation and AGN activity to explore the evolution of LIRGs which dominate the peak of the galaxy growth in the universe....

Thirty Meter Telescope Observatory and NOAO will host the second TMT Science Forum at Loews Ventana Canyon Resort in Tucson, Arizona. The TMT Science Forum is an an annual gathering of astronomers, educators, and observatory staff, who meet to explore TMT science, instrumentation, observatory operations, archiving and data processing, astronomy education, and science, technology, engineering, and math (STEM) issues. It is an opportunity for astronomers from the international TMT partners and from the US-at-large community to learn about the observatory status, discuss and plan cutting-edge science, establish collaborations, and to help shape the future of TMT. One important theme for this year's Forum will be the synergy between TMT and other facilities in the post-2020 astronomical landscape. There will be plenary sessions, an instrumentation workshop, topical science sessions and meetings of the TMT International Science Development Teams (ISDTs)....

We present our initial results on the CO rotational spectral line energy distribution (SLED) of the J to J-1 transitions from J = 4 up to 13 from Herschel SPIRE spectroscopic observations of 65 luminous infrared galaxies (LIRGs) in the Great Observatories All-Sky LIRG Survey. The observed SLEDs change on average from one peaking at J <= 4 to a broad distribution peaking around J similar to 6 to 7 as the IRAS 60-to-100 mu m color, C(60/100), increases. However, the ratios of a CO line luminosity to the total infrared luminosity, L-IR, show the smallest variation for J around 6 or 7. This suggests that, for most LIRGs, ongoing star formation (SF) is also responsible for a warm gas component that emits CO lines primarily in the mid-J regime (5 less than or similar to J less than or similar to 10). As a result, the logarithmic ratios of the CO line luminosity summed over CO (5-4), (6-5), (7-6), (8-7) and (10-9) transitions to L-IR, log R-midCO, remain largely independent of C(60/100), and show a mean value of -4.13 ( log R-midCO(SF)) and a sample standard deviation of only 0.10 for the SF-dominated galaxies. Including additional galaxies from the literature, we show, albeit with a small number of cases, the possibility that galaxies, which bear powerful interstellar shocks unrelated to the current SF, and galaxies, in which an energetic active galactic nucleus contributes significantly to the bolometric luminosity, have their R-midCO higher and lower than R-midCO(SF), respectively.

We study the behaviour of polycyclic aromatic hydrocarbon (PAH) emission in galaxies at z = 0.3-1.4 using 1868 samples from the revised catalogue of AKARI North Ecliptic Pole Deep survey. The continuous filter coverage at 2-24 mu m makes it possible to measure 8 mu m luminosity, which is dominated by PAH emission, for galaxies at up to z = 2. We compare the IR8 ( L-IR/L(8)) and 8 mu m to 4.5 mu m luminosity ratio (vL(8)/vL(4.5)) with the starburstiness, R-SB, defined as excess of specific star-formation rate over that of main-sequence galaxy. All AGN candidates were excluded from our sample using a spectral energy distribution fitting. We find vL(8)/vL(4.5) increases with starburstiness at log R-SB < 0.5 and stays constant at higher starburstiness. On the other hand, IR8 is constant at log R-SB < 0, while it increases with starburstiness at log R-SB > 0. This behaviour is seen in all redshift range of our study. These results indicate that starburst galaxies have deficient PAH emission compared with main-sequence galaxies. We also find that galaxies with extremely high vL(8)/vL(4.5) ratio have only moderate starburstiness. These results suggest that starburst galaxies have compact star-forming regions with intense radiation, which destroys PAHs, and/or have dusty HII regions resulting in a lack of ionising photons.

We present Herschel/PACS observations of extended [C II] 157.7 mu m line emission detected on similar to 1-10 kpc scales in 60 local luminous infrared galaxies ( LIRGs) from the Great Observatories All-sky LIRG Survey. We find that most of the extra-nuclear emission show [C II]/FIR ratios >= 4 x 10(-3), larger than the mean ratio seen in the nuclei, and similar to those found in the extended disks of normal star-forming galaxies and the diffuse interstellar medium of our Galaxy. The [C II] "deficits" found in the most luminous local LIRGs are therefore restricted to their nuclei. There is a trend for LIRGs with warmer nuclei to show larger differences between their nuclear and extra-nuclear [C II]/FIR ratios. We find an anti-correlation between [C II]/FIR and the luminosity surface density, SIR, for the extended emission in the spatially resolved galaxies. However, there is an offset between this trend and that found for the LIRG nuclei. We use this offset to derive a beam filling-factor for the star-forming regions within the LIRG disks of similar to 6% relative to their nuclei. We confront the observed trend to photo-dissociation region models and find that the slope of the correlation is much shallower than the model predictions. Finally, we compare the correlation found between [C II]/FIR and SIR with measurements of high-redshift starbursting IR-luminous galaxies.

We report the likely identification of a substantial population of massive M similar to 10(11) M-circle dot galaxies at z similar to 4 with suppressed star formation rates (SFRs), selected on rest-frame optical to near-IR colors from the FourStar Galaxy Evolution Survey (ZFOURGE). The observed spectral energy distributions show pronounced breaks, sampled by a set of near-IR medium-bandwidth filters, resulting in tightly constrained photometric redshifts. Fitting stellar population models suggests large Balmer/4000 angstrom breaks, relatively old stellar populations, large stellar masses, and low SFRs, with a median specific SFR of 2.9 +/- 1.8 x 10(-11) yr(-1). Ultradeep Herschel/PACS 100 mu m, 160 mu m and Spitzer/MIPS 24 mu m data reveal no dust-obscured SFR activity for 15/19(79%) galaxies. Two far-IR detected galaxies are obscured QSOs. Stacking the far-IR undetected galaxies yields no detection, consistent with the spectral energy distribution fit, indicating independently that the average specific SFR is at least 10x smaller than that of typical star-forming galaxies at z similar to 4. Assuming all far-IR undetected galaxies are indeed quiescent, the volume density is 1.8 +/- 0.7 x 10(-5) Mpc(-3) to a limit of log(10) M/M-circle dot >= 10.6, which is 10x and 80x lower than at z = 2 and z = 0.1. They comprise a remarkably high fraction (similar to 35%) of z similar to 4 massive galaxies, suggesting that suppression of star formation was efficient even at very high redshift. Given the average stellar age of 0.8 Gyr and stellar mass of 0.8x10(11) M-circle dot, the galaxies likely started forming stars before z = 5, with SFRs well in excess of 100 M-circle dot yr(-1), far exceeding that of similarly abundant UV-bright galaxies at z >= 4. This suggests that most of the star formation in the progenitors of quiescent z similar to 4 galaxies was obscured by dust.

We report the likely identification of a substantial population of massive M similar to 10(11) M-circle dot galaxies at z similar to 4 with suppressed star formation rates (SFRs), selected on rest-frame optical to near-IR colors from the FourStar Galaxy Evolution Survey (ZFOURGE). The observed spectral energy distributions show pronounced breaks, sampled by a set of near-IR medium-bandwidth filters, resulting in tightly constrained photometric redshifts. Fitting stellar population models suggests large Balmer/4000 angstrom breaks, relatively old stellar populations, large stellar masses, and low SFRs, with a median specific SFR of 2.9 +/- 1.8 x 10(-11) yr(-1). Ultradeep Herschel/PACS 100 mu m, 160 mu m and Spitzer/MIPS 24 mu m data reveal no dust-obscured SFR activity for 15/19(79%) galaxies. Two far-IR detected galaxies are obscured QSOs. Stacking the far-IR undetected galaxies yields no detection, consistent with the spectral energy distribution fit, indicating independently that the average specific SFR is at least 10x smaller than that of typical star-forming galaxies at z similar to 4. Assuming all far-IR undetected galaxies are indeed quiescent, the volume density is 1.8 +/- 0.7 x 10(-5) Mpc(-3) to a limit of log(10) M/M-circle dot >= 10.6, which is 10x and 80x lower than at z = 2 and z = 0.1. They comprise a remarkably high fraction (similar to 35%) of z similar to 4 massive galaxies, suggesting that suppression of star formation was efficient even at very high redshift. Given the average stellar age of 0.8 Gyr and stellar mass of 0.8x10(11) M-circle dot, the galaxies likely started forming stars before z = 5, with SFRs well in excess of 100 M-circle dot yr(-1), far exceeding that of similarly abundant UV-bright galaxies at z >= 4. This suggests that most of the star formation in the progenitors of quiescent z similar to 4 galaxies was obscured by dust.

Star-forming galaxies obey a remarkable ``main sequence'' correlation between their star formation rates (SFR) and stellar masses (M^ast), whose normalization (the specific star formation rate, SSFR) evolves with redshift. A minority of starbursts, with much higher SSFR, are found at all redshifts, and may be an important evolutionary stage, fueling AGN activity and building bulges and spheroids. Locally, starbursting ultraluminous infrared galaxies are the product of galaxy mergers, but this is not so clear at z > 1, where ULIRGs are hundreds of times more common, but where HST images reveal only loose correlations between irregular/disturbed morphology and starburst activity. We propose to use MOSFIRE spectroscopy to measure kinematics for 80 Herschel far-IR-selected galaxies at z 1.5, distributed over the SFR-M^ast plane. We will look for kinematic differences (larger σ_V or σ/V_rot at fixed M^ast; increased line asymmetry, and a new kinematic irregularity index optimized from numerical simulations) between main sequence and starburst galaxies that would indicate a prevalence of merger activity at higher SSFR. This program was allocated 1 night in 2013B, but was scheduled so that it will be impossible to observe our fields in 3 position angles as required. We request additional time in 2014A to complete the observations as planned....

The combination of CANDELS deep near-IR and optical HST imaging, deep Herschel photometry and vast amounts of ancillary data available highlight the 5 CANDELS fields as the best photometrically observed areas in the sky. However, relative to the GOODS fields, the COSMOS field lacks spectroscopic coverage, in particular of the Herschel- detected galaxies. While the full 2 deg^2 COSMOS field has > 20000 spectroscopic redshifts (only a fraction of which have been publicly released to date), only a few hundred of those (and only ~ 300 from the zCOSMOS-10K data release) fall within the 0.056 deg^2 COSMOS- CANDELS area. By contrast, each of the GOODS fields (each 0.044 deg^2) has 3000-4000 published redshifts. We propose to rectify this with a GEMINI/GMOS spectroscopic survey on ~350 Herschel- selected galaxies in the CANDELS COSMOS field and increase the pool of galaxies with CANDELS HST+Herschel imaging that are observable with ALMA by a factor of 2. Redshifts and spectral measurements will enhance the legacy value of the deepest HST + Herschel data, and will also allow us to study environmental effects as well as to address fundamental questions about what controls star formation in the majority of star-forming galaxies, including occasional boosting, quenching, and effects on the ISM/gas....

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Galaxy formation and evolution studies rely on the robust determination of galaxy properties such as stellar masses and star formation rates (SFR) to distinguish between star-bursting galaxies main sequence galaxies and those in the process of quenching and reveal the underlying processes causing these phenomena. We estimate SFRs of galaxies at 2 in the GOODS-S, UDS and COSMOS CANDELS fields in 3 different ways

Deep observations of sky by PACS instrument on board of Herschel Telescope at 160 μm are limited by confusion noise. Fluctuations in background flux due to undetected sources together with a high number of beams per source are the limiting factor for detecting faint sources. We have investigated the possibility of de-confusing Herschel PACS160 μm images by using strong Bayesian priors on the positions and weak priors on the fluxes of sources. Our investigation uses a semi-analytical model (SAM) to simulate PACS160 μm image with galaxies positions, redshift, and 1.6 μm fluxes being close to the observed galaxies in the HST CANDELS images of the GOODS-S field (but with spectral-energy distributions that are otherwise unconstrained by the data). Simulated Herschel images are created with the "true" fluxes from the SAM, and we attempt to recover the fluxes using their exact known positions and a several-dex wide top-hat prior on their Herschel fluxes. A Monte Carlo Markov Chain method is used to derive the posterior probability density of fluxes subject to these priors. The simulations show great promise for extracting useful photometry for sources fainter than the current confusion limit of 0.7 mJy. This technique could in principle be used to mitigate the effects of source confusion in any situation where one has prior information on positions and plausible fluxes of blended sources. For Herschel, application of the technique will improve our ability to constrain the dust content in normal galaxies at high redshift....

We will show new results from the Herschel deep imaging observations of the cosmological survey field from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS). The deep Herschel data were taken in the GOODS-S, -N, COSMOS, and UDS fields, which provide good statistics and control over cosmic variance. We will present the infrared luminosity functions derived from the Herschel data in these four CANDELS fields, and discuss their evolution....

We present the data and our analysis of mid-infrared atomic fine-structure emission lines detected in Spitzer/Infrared Spectrograph high-resolution spectra of 202 local Luminous Infrared Galaxies (LIRGs) observed as part of the Great Observatories All-sky LIRG Survey (GOALS). We readily detect emission lines of [S IV], [Ne II], [Ne v], [Ne III], [S III] 18.7 mu m, [OIV], [Fe II], [S III] 33.5, and [Si II]. More than 75% of these galaxies are classified as starburst-dominated sources in the mid-infrared, based on the [Ne v]/[Ne II] line flux ratios and equivalent width of the 6.2 mu m polycyclic aromatic hydrocarbon feature. We compare ratios of the emission-line fluxes to those predicted from stellar photo-ionization and shock-ionization models to constrain the physical and chemical properties of the gas in the starburst LIRG nuclei. Comparing the [S III]/[Ne II] and [Ne III]/[Ne II] line ratios to the Starburst-99-Mappings III models with an instantaneous burst history, the emission-line ratios suggest that the nuclear starbursts in our LIRGs have ages of 1-4.5 Myr, metallicities of 1-2 Z(circle dot), and ionization parameters of 2-8x10(7) cm s(-1). Based on the [S III](33.5 mu m)/[S III] 18.7 mu m ratios, the electron density in LIRG nuclei is typically one to a few hundred cm-3, with a median electron density of similar to 300 cm(-3), for those sources above the low density limit for these lines. We also find that strong shocks are likely present in 10 starburst-dominated sources of our sample. A significant fraction of the GOALS sources (80) have resolved neon emission-line profiles (FWHM >= 600 km s(-1)) and five show clear differences in the velocities of the [Ne III] or [Nev] emission lines, relative to [Ne II], of more than 200 km s-1. Furthermore, six starburst and five active galactic nucleus dominated LIRGs show a clear trend of increasing line width with ionization potential, suggesting the possibility of a compact energy source and stratified interstellar medium in their nuclei. We confirm a strong correlation between the sum of the [Ne II] 12.8 mu m and [Ne III] 15.5 mu m emission, as well as [S III] 33.5 mu m, with both the infrared luminosity and the 24 mu m warm dust emission measured from the spectra, consistent with all three lines tracing ongoing star formation. Finally, we find no correlation between the hardness of the radiation field or the emission-line width and the ratio of the total infrared to 8 mu m emission (IR8), a measure of the strength of the starburst and the distance of the LIRGs from the star-forming main sequence. This may be a function of the fact that the infrared luminosity and the mid-infrared fine-structure lines are sensitive to different timescales over the starburst, or that IR8 is more sensitive to the geometry of the region emitting the warm dust than the radiation field producing the Hii region emission.

We present results of the <SUP>12</SUP>CO(J=1-0) survey of 46 nearby luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS). This survey aims to obtain molecular gas mass MH<SUB>2</SUB> and to investigate the star-forming activity of local LIRGs. The estimated star formation efficiency (SFE) is 9.0±5.5 Gyr<SUP>-1</SUP> in average, which is higher than normal IR galaxies but lower than ULIRGs. No clear correlation was found either between the SFE and the 6.2μm PAH equivalent width; an indicator of AGN activity, or between the SFE and the stage of the galaxy merging....

We present the first results of a survey of the [C II]157.7 μm emission line in 241 luminous infrared galaxies (LIRGs) comprising the Great Observatories All-sky LIRG Survey (GOALS) sample, obtained with the PACS instrument on board the Herschel Space Observatory. The [C II] luminosities, L <SUB>[C II]</SUB>, of the LIRGs in GOALS range from ~10<SUP>7</SUP> to 2 × 10<SUP>9</SUP> L <SUB>☉</SUB>. We find that LIRGs show a tight correlation of [C II]/FIR with far-IR (FIR) flux density ratios, with a strong negative trend spanning from ~10<SUP>-2</SUP> to 10<SUP>-4</SUP>, as the average temperature of dust increases. We find correlations between the [C II]/FIR ratio and the strength of the 9.7 μm silicate absorption feature as well as with the luminosity surface density of the mid-IR emitting region (Σ<SUB>MIR</SUB>), suggesting that warmer, more compact starbursts have substantially smaller [C II]/FIR ratios. Pure star-forming LIRGs have a mean [C II]/FIR ~ 4 × 10<SUP>-3</SUP>, while galaxies with low polycyclic aromatic hydrocarbon (PAH) equivalent widths (EWs), indicative of the presence of active galactic nuclei (AGNs), span the full range in [C II]/FIR. However, we show that even when only pure star-forming galaxies are considered, the [C II]/FIR ratio still drops by an order of magnitude, from 10<SUP>-2</SUP> to 10<SUP>-3</SUP>, with Σ<SUB>MIR</SUB> and Σ<SUB>IR</SUB>, implying that the [C II]157.7 μm luminosity is not a good indicator of the star formation rate (SFR) for most local LIRGs, for it does not scale linearly with the warm dust emission most likely associated to the youngest stars. Moreover, even in LIRGs in which we detect an AGN in the mid-IR, the majority (2/3) of galaxies show [C II]/FIR >= 10<SUP>-3</SUP> typical of high 6.2 μm PAH EW sources, suggesting that most AGNs do not contribute significantly to the FIR emission. We provide an empirical relation between the [C II]/FIR and the specific SFR for star-forming LIRGs. Finally, we present predictions for the starburst size based on the observed [C II] and FIR luminosities which should be useful for comparing with results from future surveys of high-redshift galaxies with ALMA and CCAT.... / We present the first results of a survey of the [C II]157.7 mu m emission line in 241 luminous infrared galaxies (LIRGs) comprising the Great Observatories All-sky LIRG Survey (GOALS) sample, obtained with the PACS instrument on board the Herschel Space Observatory. The [C II] luminosities, L-[C II], of the LIRGs in GOALS range from similar to 10(7) to 2 x 10(9) L-circle dot. We find that LIRGs show a tight correlation of [C II]/FIR with far-IR (FIR) flux density ratios, with a strong negative trend spanning from similar to 10(-2) to 10(-4), as the average temperature of dust increases. We find correlations between the [C II]/FIR ratio and the strength of the 9.7 mu m silicate absorption feature as well as with the luminosity surface density of the mid-IR emitting region (Sigma(MIR)), suggesting that warmer, more compact starbursts have substantially smaller [C II]/FIR ratios. Pure star-forming LIRGs have a mean [C II]/FIR similar to 4 x 10(-3), while galaxies with low polycyclic aromatic hydrocarbon (PAH) equivalent widths (EWs), indicative of the presence of active galactic nuclei (AGNs), span the full range in [C II]/FIR. However, we show that even when only pure star-forming galaxies are considered, the [C II]/FIR ratio still drops by an order of magnitude, from 10(-2) to 10-3, with Sigma(MIR) and Sigma(IR), implying that the [C II] 157.7 mu m luminosity is not a good indicator of the star formation rate (SFR) for most local LIRGs, for it does not scale linearly with the warm dust emission most likely associated to the youngest stars. Moreover, even in LIRGs in which we detect an AGN in the mid-IR, the majority (2/3) of galaxies show [C II]/FIR >= 10-3 typical of high 6.2 mu m PAH EW sources, suggesting that most AGNs do not contribute significantly to the FIR emission. We provide an empirical relation between the [C II]/FIR and the specific SFR for star-forming LIRGs. Finally, we present predictions for the starburst size based on the observed [C II] and FIR luminosities which should be useful for comparing with results from future surveys of high-redshift galaxies with ALMA and CCAT.

Nuclear stellar cusps are defined as central excess light component in the stellar light profiles of galaxies and are suggested to be stellar relics of intense compact starbursts in the central ̃100-500 pc region of gas-rich major mergers. Here, we probe the build-up of nuclear cusps during the actual starburst phase for a complete sample of luminous infrared galaxy (LIRG) systems (85 LIRGs, with 11.4 < log [L<SUB>IR</SUB>/L<SUB>☉</SUB>] < 12.5) in the Great Observatories All-sky LIRG Survey sample. Cusp properties are derived via 2D fitting of the nuclear stellar light imaged in the near-infrared (NIR) by the Hubble Space Telescope and have been combined with mid-infrared (IR) diagnostics for active galactic nucleus (AGN)/starburst characterization. We find that nuclear stellar cusps are resolved in 76 per cent of LIRGs (merger and non-interacting galaxies). The cusp strength and luminosity increase with far-IR luminosity (excluding AGN) and merger stage, confirming theoretical models that starburst activity is associated with the build-up of nuclear stellar cusps. Evidence for ultracompact nuclear starbursts is found in ̃13 per cent of LIRGs, which have a strong unresolved central NIR light component but no significant contribution of an AGN. The nuclear NIR surface density (measured within 1 kpc radius) increases by a factor of ̃5 towards late merger stages. A careful comparison to local early-type galaxies with comparable masses reveals (a) that local (U)LIRGs have a significantly larger cusp fraction and (b) that the majority of the cusp LIRGs have host galaxy luminosities (H band) similar to core ellipticals which are roughly one order in magnitude larger than those for cusp ellipticals....

Star-forming galaxies obey a remarkable ``main sequence'' correlation between their star formation rates (SFR) and stellar masses (M^ast), whose normalization (the specific star formation rate or SSFR) evolves with redshift. A minority population of starbursts with much higher SSFR are found at all redshifts, and may represent an important stage in the transformation and evolution of galaxies, fueling AGN activity and building bulges and spheroids. Locally, starbursting ultraluminous infrared galaxies are clearly the product of galaxy mergers, but this is much less clear at z > 1, where ULIRGs are hundreds of times more common than today, but where HST observations reveal only loose correlations between irregular/disturbed morphology and starburst activity. We propose to use MOSFIRE spectroscopy to measure kinematics for >80 Herschel far-IR-selected galaxies at z 1.5, distributed over the SFR-M^ast plane. We will look for kinematic differences (larger σ_V or σ/V_rot at fixed M^ast; increased line asymmetry, and a new kinematic irregularity index optimized from numerical simulations) between main sequence and starburst galaxies that would indicate a prevalence of merger activity at higher SSFR....

The Great Observatories All-Sky LIRG Survey (GOALS) is a comprehensive, multiwavelength study of luminous infrared galaxies (LIRGs) in the local universe. Here we present low resolution Spitzer Infrared Spectrograph spectra covering 5-38 mu m and provide a basic analysis of the mid-IR spectral properties observed for nearby LIRGs. In a companion paper, we discuss detailed fits to the spectra and compare the LIRGs to other classes of galaxies. The GOALS sample of 244 nuclei in 180 luminous (10(11) <= L-IR/L-circle dot < 10(12)) and 22 ultraluminous (L-IR/L-circle dot >= 10(12)) IR galaxies represents a complete subset of the IRAS Revised Bright Galaxy Sample and covers a range of merger stages, morphologies, and spectral types. The majority (>60%) of the GOALS LIRGs have high 6.2 mu m polycyclic aromatic hydrocarbon (PAH) equivalent widths (EQW(6.2 mu m) > 0.4 mu m) and low levels of silicate absorption (s(9.7 mu m) > -1.0). There is a general trend among the U/LIRGs for both silicate depth and mid-infrared (MIR) slope to increase with increasing L-IR. U/LIRGs in the late to final stages of a merger also have, on average, steeper MIR slopes and higher levels of dust obscuration. Together, these trends suggest that as gas and dust is funneled toward the center of a coalescing merger, the nuclei become more compact and more obscured. As a result, the dust temperature increases also leading to a steeper MIR slope. The sources that depart from these correlations have very low PAH equivalent width (EQW(6.2 mu m) < 0.1 mu m) consistent with their emission being dominated by an active galactic nucleus (AGN) in the MIR. These extremely low PAH EQW sources separate into two distinct types

The Great Observatories All-sky LIRG Survey (GOALS) consists of 202 luminous infrared galaxies (LIRGs) selected from the IRAS Revised Bright Galaxy Survey. Approximately 20% of these nearby LIRGs are morphologically undisturbed disk galaxies. In contrast, surveys of LIRGs at intermediate redshift find approximately a 50%-50% split between apparently non-interacting disk galaxies and interacting/merging systems. In order to probe the nature of LIRGs that are not involved in major mergers, we compare Spitzer observations of the 38 undisturbed disk galaxies in the GOALS sample to the disk galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS) which on average are more than an order of magnitude less luminous than LIRGs in the infrared. We report the results of an investigation of possible causes for the enhanced infrared luminosity in LIRG disks compared to the more quiescent disks in SINGS....

Luminous infrared galaxies (LIRGs

We present new spectroscopic observations of the main far-infrared (FIR) emission lines detected in a sample of nearby Luminous Infrared Galaxies (LIRGs) using the PACS instrument onboard the Herschel Space Telescope. The Great Observatories All-sky LIRG Survey (GOALS) is a complete, flux-limited galaxy sample that comprises the 202 LIRGs systems (z < 0.088) included in the IRAS Revised Bright Galaxy Sample. The GOALS sample has been observed using Chandra, Galex, HST, Spitzer, and AKARI, among other first-class telescopes. Now, as part of a Herschel Open Time Cycle 1 proposal, we have obtained [CII]158μm and [OI]63μm emission line spectroscopy for all GOALS systems as well as [OIII]88μm spectroscopy for half of the sample. We confirm that LIRGs are a critical galaxy population that bridges the gap between lower luminosity star-forming galaxies showing normal [CII] / L_FIR ratios, and the most IR luminous sources (ULIRGs), which display ratios one order of magnitude smaller - the so-called [CII] "deficit". We show that while all galaxies with the lowest [CII] / L_FIR ratios present AGN signatures in their mid-IR spectra, not all mid-IR AGN-dominated sources display large [CII] deficits. Finally, we find that compactness is the main driver of the [CII] / L_FIR ratio, with more compact galaxies showing larger [CII] deficits....

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Polycyclic aromatic hydrocarbon (PAH) emission features dominate the mid-infrared spectra of star-forming galaxies and can be useful to calibrate star formation rates (SFRs) and diagnose ionized states of grains. However, the PAH 3.3 μm feature has not been studied as much as other PAH features since it is weaker than others and resides outside of Spitzer capability. In order to detect and calibrate the 3.3 μm PAH emission and investigate its potential as an SFR indicator, we carried out an AKARI mission program, AKARI mJy Unbiased Survey of Extragalactic Sources (AMUSES), and compared its sample with various literature samples. We obtained 2-5 μm low-resolution spectra of 20 flux-limited galaxies with mixed spectral energy distribution classes, which yielded the detection of the 3.3 μm PAH emission from 3 out of 20 galaxies. For the combined sample of AMUSES and literature samples, the 3.3 μm PAH luminosities correlate with the infrared luminosities of star-forming galaxies, albeit with a large scatter (1.5 dex). The correlation appears to break down at the domain of ultraluminous infrared galaxies (ULIRGs), and the power of the 3.3 μm PAH luminosity as a proxy for the infrared luminosity is hampered at log[L <SUB>PAH3.3</SUB> erg<SUP>-1</SUP> s<SUP>-1</SUP>] > ~42.0. Possible origins for this deviation in the correlation are discussed, including contributions from active galactic nuclei and strongly obscured young stellar objects, and the destruction of PAH molecules in ULIRGs.... / Polycyclic aromatic hydrocarbon (PAH) emission features dominate the mid-infrared spectra of star-forming galaxies and can be useful to calibrate star formation rates (SFRs) and diagnose ionized states of grains. However, the PAH 3.3 mu m feature has not been studied as much as other PAH features since it is weaker than others and resides outside of Spitzer capability. In order to detect and calibrate the 3.3 mu m PAH emission and investigate its potential as an SFR indicator, we carried out an AKARI mission program, AKARI mJy Unbiased Survey of Extragalactic Sources (AMUSES), and compared its sample with various literature samples. We obtained 2-5 mu m low-resolution spectra of 20 flux-limited galaxies with mixed spectral energy distribution classes, which yielded the detection of the 3.3 mu m PAH emission from 3 out of 20 galaxies. For the combined sample of AMUSES and literature samples, the 3.3 mu m PAH luminosities correlate with the infrared luminosities of star-forming galaxies, albeit with a large scatter (1.5 dex). The correlation appears to break down at the domain of ultraluminous infrared galaxies (ULIRGs), and the power of the 3.3 mu m PAH luminosity as a proxy for the infrared luminosity is hampered at log[L-PAH3.3 erg(-1) s(-1)] > similar to 42.0. Possible origins for this deviation in the correlation are discussed, including contributions from active galactic nuclei and strongly obscured young stellar objects, and the destruction of PAH molecules in ULIRGs.

Polycyclic aromatic hydrocarbon (PAH) emission features dominate the mid-infrared spectra of star-forming galaxies and can be useful to calibrate star formation rates (SFRs) and diagnose ionized states of grains. However, the PAH 3.3 mu m feature has not been studied as much as other PAH features since it is weaker than others and resides outside of Spitzer capability. In order to detect and calibrate the 3.3 mu m PAH emission and investigate its potential as an SFR indicator, we carried out an AKARI mission program, AKARI mJy Unbiased Survey of Extragalactic Sources (AMUSES), and compared its sample with various literature samples. We obtained 2-5 mu m low-resolution spectra of 20 flux-limited galaxies with mixed spectral energy distribution classes, which yielded the detection of the 3.3 mu m PAH emission from 3 out of 20 galaxies. For the combined sample of AMUSES and literature samples, the 3.3 mu m PAH luminosities correlate with the infrared luminosities of star-forming galaxies, albeit with a large scatter (1.5 dex). The correlation appears to break down at the domain of ultraluminous infrared galaxies (ULIRGs), and the power of the 3.3 mu m PAH luminosity as a proxy for the infrared luminosity is hampered at log[L-PAH3.3 erg(-1) s(-1)] > similar to 42.0. Possible origins for this deviation in the correlation are discussed, including contributions from active galactic nuclei and strongly obscured young stellar objects, and the destruction of PAH molecules in ULIRGs.

Luminous (LIRGs; log (L-IR/L-circle dot) = 11.00-11.99) and ultraluminous infrared galaxies (ULIRGs; log (L-IR/L-circle dot) = 12.00-12.99) are the most extreme star-forming galaxies in the universe. The local (U)LIRGs provide a unique opportunity to study their multi-wavelength properties in detail for comparison with their more numerous counterparts at high redshifts. We present common large aperture photometry at radio through X-ray wavelengths and spectral energy distributions (SEDs) for a sample of 53 nearby (z < 0.083) LIRGs and 11 ULIRGs spanning log (L-IR/L-circle dot) = 11.14-12.57 from the flux-limited (f(60 mu m) > 5.24 Jy) Great Observatories All-sky LIRG Survey. The SEDs for all objects are similar in that they show a broad, thermal stellar peak (similar to 0.3-2 mu m), and a dominant FIR (similar to 40-200 mu m) thermal dust peak, where vL(v) (60 mu m)/vL(v) (V) increases from similar to 2 to 30 with increasing L-IR. When normalized at IRAS 60 mu m, the largest range in the luminosity ratio, R(lambda) = log[vL(v)(lambda)/vL(v) (60 mu m)], observed over the full sample is seen in the hard X-rays (HX = 2-10 keV), where Delta R-HX = 3.73 ((R) over bar (HX) = -3.10). A small range is found in the radio (1.4 GHz), Delta R-1.4 GHz = 1.75, where the mean ratio is largest, ((R) over bar (1.4 GHz) = -5.81). Total infrared luminosities, L-IR(8-1000 mu m), dust temperatures, and dust masses were computed from fitting thermal dust emission modified blackbodies to the mid-infrared (MIR) through submillimeter SEDs. The new results reflect an overall similar to 0.02 dex lower luminosity than the original IRAS values. Total stellar masses were computed by fitting stellar population synthesis models to the observed near-infrared (NIR) through ultraviolet (UV) SEDs. Mean stellar masses are found to be log(M-*/M-circle dot) = 10.79 +/- 0.40. Star formation rates have been determined from the infrared (SFRIR similar to 45M(circle dot) yr(-1)) and from the monochromatic UV luminosities (SFRUV similar to 1.3M(circle dot) yr(-1)), respectively. Multi-wavelength active galactic nucleus (AGN) indicators have be used to select putative AGNs

Results of observations with the Spitzer, Hubble, GALEX, Chandra, and XMM-Newton space telescopes are presented for the luminous infrared galaxy (LIRG) merger Markarian 266. The SW (Seyfert 2) and NE (LINER) nuclei reside in galaxies with Hubble types SBb (pec) and S0/a (pec), respectively. Both companions are more luminous than L* galaxies and they are inferred to each contain a approximate to 2.5 x 10(8) M-circle dot black hole. Although the nuclei have an observed hard X-ray flux ratio of f(X)(NE)/f(X)(SW) = 6.4, Mrk 266 SW is likely the primary source of a bright Fe K alpha line detected from the system, consistent with the reflection-dominated X-ray spectrum of a heavily obscured active galactic nucleus (AGN). Optical knots embedded in an arc with aligned radio continuum radiation, combined with luminous H-2 line emission, provide evidence for a radiative bow shock in an AGN-driven outflow surrounding the NE nucleus. A soft X-ray emission feature modeled as shock-heated plasma with T similar to 10(7) K is cospatial with radio continuum emission between the galaxies. Mid-infrared diagnostics provide mixed results, but overall suggest a composite system with roughly equal contributions of AGN and starburst radiation powering the bolometric luminosity. Approximately 120 star clusters have been detected, with most having estimated ages less than 50 Myr. Detection of 24 mu m emission aligned with soft X-rays, radio continuum, and ionized gas emission extending similar to 34 '' (20 kpc) north of the galaxies is interpreted as similar to 2 x 10(7) M-circle dot of dust entrained in an outflowing superwind. At optical wavelengths this Northern Loop region is resolved into a fragmented morphology indicative of Rayleigh-Taylor instabilities in an expanding shell of ionized gas. Mrk 266 demonstrates that the dust "blowout" phase can begin in a LIRG well before the galaxies fully coalesce during a subsequent ultraluminous infrared galaxy (ULIRG) phase, and rapid gas consumption in luminous dual AGNs with kiloparsec-scale separations early in the merger process may explain the paucity of detected binary QSOs (with parsec-scale orbital separations) in spectroscopic surveys. An evolutionary sequence is proposed representing a progression from dual to binary AGNs, accompanied by an increase in observed L-x/L-ir ratios by over two orders of magnitude.

We propose a co-ordinated multi-observatory survey at the North Ecliptic Pole. This field is the natural extragalactic deep field location for most space observatories (e.g. containing the deepest Planck, WISE and eROSITA data), is in the continuous viewing zones for e.g. Herschel, HST, JWST, and is a natural high-visibility field for the L2 halo orbit of SPICA with deep and wide-field legacy surveys already planned. The field is also a likely deep survey location for the forthcoming Euclid mission. It is already a multi-wavelength legacy field in its own right (e.g. AKARI, LOFAR, SCUBA-2)

By cross-correlating the AKARI all-sky survey in six infrared (IR) bands (9, 18, 65, 90, 140 and 160 mu m) with the Sloan Digital Sky Survey (SDSS) galaxies, we identified 2357 IR galaxies with a spectroscopic redshift. This is not just one of the largest samples of local IR galaxies, but AKARI provides crucial far-IR (FIR) bands for accurately measuring the galaxy spectral energy distribution (SED) across the peak of the dust emission at > 100 mu m. By fitting modern IR SED models to the AKARI photometry, we measured the total infrared luminosity (LIR) of individual galaxies. Using this L-IR, we constructed the luminosity functions (LF) of IR galaxies at a median redshift of z = 0.031. The LF agrees well with that at z = 0.0082 (the Revised Bright Galaxy Sample), showing smooth and continuous evolution towards higher redshift LFs measured in the AKARI North Ecliptic Pole (NEP) deep field. By integrating the IR LF weighted by LIR, we measured the local cosmic IR luminosity density of Omega(IR) = (3.8(-1.2)(+5.8)) x 10(8) L-circle dot Mpc(-3). We separate galaxies into active galactic nuclei (AGN), star-forming galaxies (SFG) and composite by using the [N-II]/H alpha versus [O III]/H beta line ratios. The fraction of AGN shows a continuous increase with increasing LIR from 25 to 90 per cent at 9 < log L-IR < 12.5. The SFRH alpha and L[ O III] show good correlations with LIR for SFG and AGN, respectively. The self-absorption-corrected H alpha/H beta ratio shows a weak increase with LIR with a substantial scatter. When we separate IR LFs into contributions from AGN and SFG, the AGN contribution becomes dominant at LIR > 10(11) L-circle dot, coinciding with the break of both the SFG and AGN IR LFs. At LIR = 10(11) L-circle dot, SFG dominates IR LFs. Only 1.1 +/- 0.1 per cent of Omega(IR) is produced by luminous infrared galaxies (LIR > 10(11) L-circle dot), and only 0.03 +/- 0.01 per cent by ultraluminous infrared galaxies (L-IR > 10(12) L-circle dot) in the local Universe. Compared with high-redshift results from the AKARI NEP deep survey, we observed a strong evolution of Omega(SFG)(IR) proportional to (1 + z)(4.1 +/- 0.4) and Omega(AGN)(IR) proportional to (1 + z)(4.1 +/- 0.5). Our results show that all of our measured quantities (IR LFs, L*, Omega(AGN)(IR), Omega(SFG)(IR)) show smooth and steady increase from lower redshift (the Revised Bright Galaxy Sample) to higher redshift (the AKARI NEP deep survey).

This paper describes a pilot study into the spectral energy distribution (SED) fitting and the derivation of physical parameters for 19 galaxies observed as part of the Great Observatories All-sky LIRG Survey (GOALS) survey as observed with the Spitzer Space Telescope. For this we have used the pan-spectral fitting tools developed in a series of papers by Dopita and his co-workers. We show that the standard Lee and Draine `astronomical silicate' model cannot provide a good fit to the silicate absorption features as observed in the heavily dust-extinguished ( A <SUB>V</SUB>̃50 mag.) starbursts. We have derived an empirical fit to the `starburst silicate' absorption in these objects. This absorption curve is consistent with the silicate grains being systematically larger in starburst environments than in the local Galactic interstellar medium. We demonstrate the sensitivity of the SED fitting to each of the fitted parameters, and derive these parameters for those galaxies which do not have an embedded AGN. This technique is simple and provides reasonably robust and uniform parameters for the starburst, especially as far as the star formation rate, population of old stars, compactness of the starburst region and total foreground extinction are concerned. However, the chemical abundances and the optical extinction cannot be reliably determined by this analysis, and optical SEDs will also be required to provide a complete characterization of the starburst region and of the surrounding galaxy.... / This paper describes a pilot study into the spectral energy distribution (SED) fitting and the derivation of physical parameters for 19 galaxies observed as part of the Great Observatories All-sky LIRG Survey (GOALS) survey as observed with the Spitzer Space Telescope. For this we have used the pan-spectral fitting tools developed in a series of papers by Dopita and his co-workers. We show that the standard Lee and Draine 'astronomical silicate' model cannot provide a good fit to the silicate absorption features as observed in the heavily dust-extinguished (A (V similar to)50 mag.) starbursts. We have derived an empirical fit to the 'starburst silicate' absorption in these objects. This absorption curve is consistent with the silicate grains being systematically larger in starburst environments than in the local Galactic interstellar medium. We demonstrate the sensitivity of the SED fitting to each of the fitted parameters, and derive these parameters for those galaxies which do not have an embedded AGN. This technique is simple and provides reasonably robust and uniform parameters for the starburst, especially as far as the star formation rate, population of old stars, compactness of the starburst region and total foreground extinction are concerned. However, the chemical abundances and the optical extinction cannot be reliably determined by this analysis, and optical SEDs will also be required to provide a complete characterization of the starburst region and of the surrounding galaxy.

We present a 190-307 GHz broadband spectrum obtained with Z-Spec of NGC 1068 with new measurements of molecular rotational transitions. After combining our measurementswith those previously published and considering the specific geometry of this Seyfert 2 galaxy, we conduct amulti-species Bayesian likelihood analysis of the density, temperature, and relative molecular abundances of HCN, HNC, CS, and HCO+. We find that these molecules trace warm (T > 100 K) gas of H-2 number densities 10(4.2)-10(4.9) cm(-3). Our models also place strong constraints on the column densities and relative abundances of these molecules, as well as on the total mass in the circumnuclear disk. Using the uniform calibration afforded by the broad Z-Spec bandpass, we compare our line ratios to X-ray-dominated region (XDR) and photon-dominated region models. The majority of our line ratios are consistent with the XDR models at the densities indicated by the likelihood analysis, lending substantial support to the emerging interpretation that the energetics in the circumnuclear disk of NGC 1068 are dominated by accretion onto an active galactic nucleus.

We present results of Hubble Space Telescope (HST) NICMOS H-band imaging of 73 of the most luminous (i.e., log[L-IR/L-circle dot] > 11.4) infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. This data set combines multi-wavelength imaging and spectroscopic data from space-based (Spitzer, HST, GALEX, and Chandra) and ground-based telescopes. In this paper, we use high-resolution near-infrared data to recover nuclear structure that is obscured by dust at optical wavelengths and measure the evolution in this structure along the merger sequence. A large fraction of all galaxies in our sample possess double nuclei (similar to 63%) or show evidence for triple nuclei (similar to 6%). Half of these double nuclei are not visible in the HST B-band images due to dust obscuration. The majority of interacting LIRGs have remaining merger timescales of 0.3-1.3 Gyr, based on the projected nuclear separations and the mass ratio of nuclei. We find that the bulge luminosity surface density L-Bulge/R-Bulge(2) increases significantly along the merger sequence (primarily due to a decrease of the bulge radius), while the bulge luminosity shows a small increase toward late merger stages. No significant increase of the bulge Sersic index is found. LIRGs that show no interaction features have on average a significantly larger bulge luminosity, suggesting that non-merging LIRGs have larger bulge masses than merging LIRGs. This may be related to the flux-limited nature of the sample and the fact that mergers can significantly boost the IR luminosity of otherwise low luminosity galaxies. We find that the projected nuclear separation is significantly smaller for ULIRGs (median value of 1.2 kpc) than for LIRGs (median value of 6.7 kpc), suggesting that the LIRG phase appears earlier in mergers than the ULIRG phase.

We present a statistical analysis of the mid-infrared (MIR) spectra of 248 luminous infrared (IR) galaxies (LIRGs) which comprise the Great Observatories All-sky LIRG Survey (GOALS) observed with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. The GOALS sample enables a direct measurement of the relative contributions of star formation and active galactic nuclei (AGNs) to the total IR emission from a large sample of local LIRGs. The AGN contribution to the MIR emission (f(AGN)) is estimated by employing several diagnostics based on the properties of the [Ne v], [O IV], and [Ne II] fine-structure gas emission lines, the 6.2 mu m polycyclic aromatic hydrocarbon (PAH), and the shape of the MIR continuum. We find that 18% of all LIRGs contain an AGN and that in 10% of all sources the AGN contributes more than 50% of the total IR luminosity. Summing up the total IR luminosity contributed by AGNs in all our sources suggests that AGNs supply similar to 12% of the total energy emitted by LIRGs. The average spectrum of sources with an AGN looks similar to the average spectrum of sources without an AGN, but it has lower PAH emission and a flatter MIR continuum. AGN-dominated LIRGs have higher IR luminosities, warmer MIR colors, and are found in interacting systems more often than pure starburst LIRGs. However, we find no linear correlations between these properties and f(AGN). We used the IRAC colors of LIRGs to confirm that finding AGNs on the basis of their MIR colors may miss similar to 40% of AGN-dominated (U)LIRGs.

Infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and active galactic nuclei (AGN) evolution, since their most intense stages are often obscured by dust. However, local IR luminosity function estimates today are still based on the IRAS survey in the 1980s, with wavelength coverage only up to 100 mu m. The AKARI IR space telescope performed an all-sky survey in six IR bands (9, 18, 65, 90, 140 and 160 mu m) with 3-10 times better sensitivity, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can much more precisely measure the total infrared luminosity (L-TIR) of individual galaxies, and thus, the total infrared luminosity density in the local Universe. By fitting modern IR spectral energy distribution (SED) models, we have remeasured L-TIR of the IRAS Revised Bright Galaxy Sample, which is a complete sample of local galaxies with S-60 mu m > 5.24 Jy. We present mid-IR monochromatic luminosity (nu L-nu) to L-TIR correlations for Spitzer 8 mu m, AKARI 9 mu m, IRAS 12 mu m, WISE 12 mu m, ISO 15 mu m, AKARI 18 mu m, WISE 22 mu m and Spitzer 24 mu m filters. These measures of L-MIR are well correlated with L-TIR, with scatter in the range 13-44 per cent. The best-fitting L-MIR-to-L-TIR conversions provide us with estimates of L-TIR using only a single MIR band, in which several deep all-sky surveys are becoming available such as AKARI MIR and WISE. Although we have found some overestimates of L-TIR by IRAS due to contaminating cirrus/sources, the resulting AKARI IR luminosity function (LF) agrees well with that from IRAS. We integrate the LF weighted by L-TIR to obtain a cosmic IR luminosity density of (TIR) = (8.5+1.5(-2.3)) x 107 L-circle dot Mpc-3, of which 7 +/- 1 per cent is produced by luminous infrared galaxies (LIRGs) (L-TIR > 1011 L-circle dot), and only 0.4 +/- 0.1 per cent is from ultraluminous infrared galaxies (ULIRGs) (L-TIR > 1012 L-circle dot) in the local Universe, in stark contrast to high-redshift results. We separate the contributions from AGN and star-forming galaxies (SFGs). The SFG IR LF shows a steep decline at the bright end. Combined with high-redshift results from the AKARI NEP deep survey, these data show a strong evolution of SFTIR proportional to (1 + z)4.0 +/- 0.5 and AGN(TIR) proportional to (1 + z)4.4 +/- 0.4. For AGN(TIR), the ULIRG contribution exceeds that from LIRGs already by z similar to 1. A rapid evolution in both AGN(TIR) and SFG(TIR) suggests the correlation between star formation and black hole accretion rate continues up to higher redshifts. We compare the evolution of AGN(TIR) to that of X-ray luminosity density. The AGN(TIR)/(X-ray) AGN ratio shows a possible increase at z > 1, suggesting an increase of obscured AGN at z > 1.

We present AKARI near-infrared (NIR) and Spitzer mid-infrared (MIR) spectroscopy of both luminous infrared galaxies (LIRGs) and ultra luminous infrared galaxies (ULIRGs) from the Revised Bright Galaxy Sample and the 1 Jy sample, respectively. Luminous infrared galaxies emit more of their bolometric luminosity in the infrared (8-1000 microns) than in all other parts of the spectrum combined. It appears that the infrared luminosity originates from a combination of starburst and active galactic nucleus (AGN) (cf. Sanders & Mirabel 1996 and references therein). For the first time we combine emission line fluxes in both 2.5-5 micron data from AKARI with 5-35 micron data from Spitzer to derive new infrared diagnostic diagrams that can distinguish between starburst and AGN activity in heavily obscured (U)LIRGs. Previous attempts at classifying these galaxies in the optical regime have proven to be very difficult due to the heavy dust extinction from buried AGNs. However since infrared radiation is affected much less by dust than in the optical, we show that the infrared emission line diagnostic [Ne III]/[Ne II] vs. [O IV]/Br-alpha appears most promising in separating starburst-driven ULIRGs and AGN-driven ULIRGs. In addition the diagnostic [Ne III]/[Ne II] vs. [S III]/Br-alpha also appears to be moderately effective in separating ULIRGs driven by starbursts and AGNs, while the [NeIII]/[Ne II] vs. [S IV]/Br-alpha ratio does a relatively poor job. These results were then compared to theoretical models generated by the Starburst99 and Mappings codes....

We present an analysis of the extended mid-infrared (MIR) emission of the Great Observatories All-Sky LIRG Survey sample based on 5-15 mu m low-resolution spectra obtained with the Infrared Spectrograph on Spitzer. We calculate the fraction of extended emission (FEE) as a function of wavelength for the galaxies in the sample, FEE lambda, defined as the fraction of the emission which originates outside of the unresolved component of a source at a given distance. We find that the FEE lambda varies from one galaxy to another, but we can identify three general types of FEE lambda

We present a three-pointing study of the molecular gas in the starburst nucleus of M82 based on 190-307 GHz spectra obtained with Z-Spec at the Caltech Submillimeter Observatory. We present intensity measurements, detections, and upper limits, for 20 transitions, including several new detections of CS, HNC, C(2)H, H(2)CO, and CH(3)CCH lines. We combine our measurements with previously published measurements at other frequencies for HCN, HNC, CS, C(34)S, and HCO(+) in a multi-species likelihood analysis constraining gas mass, density and temperature, and the species' relative abundances. We find some (1.7-2.7) x 10(8) M(circle dot) of gas with n(H2) between (1-6) x 10(4) cm(-3) and T > 50 K. While the mass and temperature are comparable to values inferred from mid-J CO transitions, the thermal pressure is a factor of 10-20 greater. The molecular interstellar medium is largely fragmented and is subject to ultraviolet irradiation from the star clusters. It is also likely subject to cosmic rays and mechanical energy input from the supernovae, and is warmer on average than the molecular gas in the massive star formation (SF) regions in the Milky Way. The typical conditions in the dense gas in M82's central kiloparsec appear unfavorable for further SF; if any appreciable stellar populations are currently forming, they are likely biased against low-mass stars, producing a top-heavy initial mass function.

An analysis of data from the Spitzer Space Telescope, Hubble Space Telescope, Chandra X-ray Observatory, and AKARI Infrared Astronomy Satellite is presented for the z = 0.036 merging galaxy system II Zw 096 (CGCG 448-020). Because II Zw 096 has an infrared luminosity of log(L-IR/L-circle dot) = 11.94, it is classified as a Luminous Infrared Galaxy (LIRG), and was observed as part of the Great Observatories All-sky LIRG Survey (GOALS). The Spitzer data suggest that 80% of the total infrared luminosity comes from an extremely compact, red source not associated with the nuclei of the merging galaxies. The Spitzer mid-infrared spectra indicate no high-ionization lines from a buried active galactic nucleus in this source. The strong detection of the 3.3 mu m and 6.2 mu m polycyclic aromatic hydrocarbon emission features in the AKARI and Spitzer spectra also implies that the energy source of II Zw 096 is a starburst. Based on Spitzer infrared imaging and AKARI near-infrared spectroscopy, the star formation rate is estimated to be 120 M-circle dot yr(-1) and >45 M-circle dot yr(-1), respectively. Finally, the high-resolution B-, I-, and H-band images show many star clusters in the interacting system. The colors of these clusters suggest at least two populations-one with an age of 1-5 Myr and one with an age of 20-500 Myr, reddened by 0-2 mag of visual extinction. The masses of these clusters span a range between 10(6) and 10(8) M-circle dot. This starburst source is reminiscent of the extranuclear starburst seen in NGC 4038/9 (the Antennae Galaxies) and Arp 299 but approximately an order of magnitude more luminous than the Antennae. The source is remarkable in that the off-nuclear infrared luminosity dominates the entire system.

Ultraluminous Infrared Galaxies (ULIRGs) have the power output of quasars, yet they emit nearly all of their energy in the mid to far-infrared. While rare in the local Universe, ULIRGs play an increasingly important role in the evolving star formation rate density at high redshift, and they may account for a major fraction of the far-infrared background. Nearly 200 low-redshift ULIRGs have been observed with the IRS on Spitzer during the cryogenic phase of the mission. The IRS spectra of ULIRGs show a great diversity in their properties (slopes, emission line ratios, PAH strengths, extinction), and when coupled with near-infrared and far-infrared photometry, they have been used to quantify the amount of energy produced by AGN and starbursts. The 2-5 micron window is critical for measuring the contribution of hot (~1000K) AGN-heated dust to the emerging SED, yet nearly half of the ULIRGs observed with the IRS have no existing IRAC photometry to cover this wavelength range. Here we propose to complete the Spitzer observations of this important population by observing 83 ULIRGs and 23 PG QSOs (used as templates to understand the hot dust contribution in ULIRGs) with IRAC at 3.6 and 4.5 microns to fill in the missing part of their SEDs, and provide a lasting mid-infrared legacy for studies of ULIRGs and AGN at high-redshift with future generations of IR facilties....

The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete sample of 202 luminous infrared galaxies (LIRGs) selected from the IRAS Revised Bright Galaxy Sample (RBGS). The galaxies span the full range of interaction stages, from isolated galaxies to interacting pairs to late stage mergers. We present a comparison of the UV and infrared properties of 135 galaxies in GOALS observed by GALEX and Spitzer. For interacting galaxies with separations greater than the resolution of GALEX and Spitzer (similar to 2 ''-6 ''), we assess the UV and IR properties of each galaxy individually. The contribution of the FUV to the measured star formation rate (SFR) ranges from 0.2% to 17.9%, with a median of 2.8% and a mean of 4.0% +/- 0.4%. The specific star formation rate (SSFR) of the GOALS sample is extremely high, with a median value (3.9 x 10(-10) yr(-1)) that is comparable to the highest SSFRs seen in the Spitzer Infrared Nearby Galaxies Survey sample. We examine the position of each galaxy on the IR excess-UV slope (IRX-beta) diagram as a function of galaxy properties, including IR luminosity and interaction stage. The LIRGs on average have greater IR excesses than would be expected based on their UV colors if they obeyed the same relations as starbursts with L(IR) < 10(11) L(circle dot) or normal late-type galaxies. The ratio of L(IR) to the value one would estimate from the IRX-beta relation published for lower luminosity starburst galaxies ranges from 0.2 to 68, with a median value of 2.7. A minimum of 19% of the total IR luminosity in the RBGS is produced in LIRGs and ultraluminous infrared galaxies with red UV colors (beta > 0). Among resolved interacting systems, 32% contain one galaxy which dominates the IR emission while the companion dominates the UV emission. Only 21% of the resolved systems contain a single galaxy which dominates both wavelengths.

Aims. Dust-obscured star-formation increases with increasing intensity and increasing redshift. We aim to reveal the cosmic star-formation history obscured by dust using deep infrared observation with AKARI. Methods. We constructed restframe 8 mu m, 12 mu m, and total infrared (TIR) luminosity functions (LFs) at 0.15 < z < 2.2 using 4128 infrared sources in the AKARI NEP-deep field. A continuous filter coverage in the mid-IR wavelength (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and 24 mu m) by the AKARI satellite allowed us to estimate restframe 8 mu m and 12 mu m luminosities without using a large extrapolation based on an SED fit, which was the largest uncertainty in previous work. Results. We find that all 8 mu m (0.38 < z < 2.2), 12 mu m (0.15 < z < 1.16), and TIR LFs (0.2 < z < 1.6) show continuous and strong evolution toward higher redshift. Our direct estimate of 8 mu m LFs is useful since previous work often had to use a large extrapolation from the Spitzer 24 mu m to 8 mu m, where SED modeling is more difficult because of the PAH emissions. In terms of cosmic infrared luminosity density (Omega(IR)), which was obtained by integrating analytic fits to the LFs, we find good agreement with previous work at z < 1.2. We find the Omega(IR) evolves as proportional to(1 + z)(4.4 +/- 1.0). When we separate contributions to Omega(IR) by LIRGs and ULIRGs, we found more IR luminous sources are increasingly more important at higher redshift. We find that the ULIRG (LIRG) contribution increases by a factor of 10 (1.8) from z = 0.35 to z = 1.4.

<BR /> Aims

The Great Observatories All-sky LIRG Survey (GOALS) combines data from NASA's Spitzer, Chandra, Hubble and GALEX observatories, together with ground-based data, into a comprehensive imaging and spectroscopic survey of over 200 low-redshift (z < 0.09) Luminous Infrared Galaxies (LIRGs). The GOALS galaxies span the full range of nuclear spectral types and interaction stages. An important aspect of GOALS is a direct comparison of the mid-infrared spectral properties and the global UV emission in LIRGs. While most LIRGs appear powered by star formation, nearly 25% show evidence for AGN in their Spitzer spectra. Over the entire sample, we estimate that about 12% of the bolometric luminosity is generated by AGN. The UV properties are extremely diverse, with IR/FUV flux ratios ranging from 12-2600. We will discuss the relation between the IR and UV properties of the GOALS galaxies, and the implications for studying LIRGs at high redshift....

Luminous infrared galaxies (LIRGs) have infrared luminosities (LIR) above 10<SUP>11</SUP> solar luminosities and a wide range of morphologies ranging from isolated spirals to late-stage mergers. Their infrared emission is believed to originate from powerful starbursts and/or AGN, but a complete accounting of the relative importance of each has not been completed using a large, sample until now. The Great Observatories All-Sky LIRG Survey (GOALS) consists of a multi-wavelength imaging and spectroscopic Spitzer, Hubble, Chandra and GALEX survey of a flux-limited sample of 202 LIRGs in the local Universe (z < 0.09). In addition, we have recently obtained 2.5-5 micron spectra of the GOALS sample with AKARI. The AKARI spectra are dominated by 3.3 micron PAH and Br-alpha emission features , as well as hot dust continuum emission. We will discuss the AKARI results, and compare these to the Spitzer data in order to present a complete picture of the relative importance of starbursts and AGN to LIRGs as seen in their infrared spectra from 3-40 microns....

I outline some results from the Z-Spec instrument at the CSO and present a concept for CCAT survey spectrometer....

We present the first broadband lambda = 1 mm spectrum toward the z = 2.56 Cloverleaf quasar, obtained with Z-Spec, a grating spectrograph on the 10.4 m Caltech Submillimeter Observatory. The 190-305 GHz observation band corresponds to the rest frame 272-444 mu m, and we measure the dust continuum as well as all four transitions of carbon monoxide ( CO) lying in this range. The power-law dust emission, F(nu) = 14 mJy (nu/240 GHz)(3.9) is consistent with the published continuum measurements. The CO J = 6 -> 5, J = 8 -> 7, and J = 9 -> 8 measurements are the first, and now provide the highest-J CO information in this source. Our measured CO intensities are very close to the previously published interferometric measurements of J = 7 -> 6, and we use all available transitions and our (13)CO upper limits to constrain the physical conditions in the Cloverleaf molecular gas disk. We find a large mass (2-50 x 10(9)M(circle dot)) of highly excited gas with thermal pressure nT > 10(6) K cm(-3). The ratio of the total CO cooling to the far-IR dust emission exceeds that in the local dusty galaxies, and we investigate the potential heating sources for this bulk of warm molecular gas. We conclude that both UV photons and X-rays likely contribute, and discuss implications for a top-heavy stellar initial mass function arising in the X-ray-irradiated starburst. Finally, we present tentative identifications of other species in the spectrum, including a possible detection of the H(2)O 2(0,2) -> 1(1,1) transition at lambda(rest) = 303 mu m.

The Great Observatories All-Sky LIRG Survey (GOALS20 ) combines data from NASA’s Spitzer Space Telescope, Chandra X-Ray Observatory, Hubble Space Telescope (HST), and Galaxy Evolution Explorer (GALEX) observatories, together with ground-based data, into a comprehensive imaging and spectroscopic survey of over 200 low-redshift (z < 0.088), Luminous Infrared Galaxies (LIRGs). The LIRGs are a complete subset of the IRAS Revised Bright Galaxy Sample (RBGS), which comprises 629 extragalactic objects with 60 μm flux densities above 5.24 Jy, and Galactic latitudes above five degrees. The LIRGs targeted in GOALS span the full range of nuclear spectral types defined via traditional optical line-ratio diagrams (type-1 and type-2 AGN, LINERs, and starbursts) as well as interaction stages (major mergers, minor mergers, and isolated galaxies). They provide an unbiased picture of the processes responsible for enhanced infrared emission in galaxies in the local Universe. As an example of the analytic power of the multiwavelength GOALS data set, we present Spitzer, Chandra, HST, and GALEX images and spectra for the interacting system VV 340 (IRAS F14547 + 2449). The Spitzer MIPS imaging data indicates that between 80-95% of the total far-infrared emission (or about 5 × 10<SUP>11</SUP> L<SUB>☉</SUB>) originates in VV 340 north. While the Spitzer IRAC colors of VV 340 north and south are consistent with star-forming galaxies, both the Spitzer IRS and Chandra ACIS data indicate the presence of an AGN in VV 340 north. The observed line fluxes, without correction for extinction, imply that the AGN accounts for less than 10%-20% of the observed infrared emission. The X-ray data are consistent with a heavily absorbed (N<SUB>H</SUB>≥10<SUP>24</SUP> cm<SUP>-2</SUP>) AGN. The GALEX far and near-UV fluxes imply a extremely large infrared “excess” (IRX) for the system (F<SUB>IR</SUB>/F<SUB>fuv</SUB> ̃ 81) which is well above the correlation seen in starburst galaxies. Most of this excess is driven by VV 340 N, which has an IR excess of nearly 400. The VV 340 system seems to be comprised of two very different galaxies

We present observations of the luminous infrared galaxy IIZw96 taken with the Spitzer Space Telescope, as well as HST. IIZw96 was selected from the Great Observatories All-sky LIRG Survey (GOALS). For the first time, we show high spatial resolution mid and far-infrared data which demonstrates that the majority of the bolometric luminosity originates from a highly obscured region not associated with the nuclei of the merging galaxies. Mid-infrared colors and spectra suggest that the luminosity originates in a deeply embedded starburst region....

There is a huge gap between the properties of red-sequence selected massive galaxy clusters at z < 1 and Lyman-break selected proto-clusters at z > 3. It is important to understand when and how the z > 3 proto-clusters evolve into passive clusters at z < 1. We aim to fill this cluster desert by using space-based N4 (4 mu m) imaging with AKARI. The z'-N4 color is a powerful separator of cluster galaxies at z > 1, taking advantage of the 4000 angstrom break and the 1.6 mu m bump. We carefully selected 16 promising cluster candidates at 0.9 < z < 1.7, which all show an obvious over-density of galaxies and a prominent red-sequence. At this redshift range, the mid-infrared S-15 mu m/S-9 mu m flux ratio is an extinction-free indicator of galaxy star-formation activity due to the redshifted PAH emission lines (6.2, 7.7, and 8.6 mu m). We show statistically that the cluster galaxies have a lower S-15 mu m/S-9 mu m flux ratio than do field galaxies, i.e., cluster galaxies already have lower star-formation activity at 0.9 < z < 1.7, pushing the fort-nation epoch of these galaxy clusters to a higher redshift.

There is a huge gap between the properties of red-sequence selected massive galaxy clusters at z < 1 and Lyman-break selected proto-clusters at z > 3. It is important to understand when and how the z > 3 proto-clusters evolve into passive clusters at z < 1. We aim to fill this cluster desert by using space-based N4 (4 mu m) imaging with AKARI. The z'-N4 color is a powerful separator of cluster galaxies at z > 1, taking advantage of the 4000 angstrom break and the 1.6 mu m bump. We carefully selected 16 promising cluster candidates at 0.9 < z < 1.7, which all show an obvious over-density of galaxies and a prominent red-sequence. At this redshift range, the mid-infrared S-15 mu m/S-9 mu m flux ratio is an extinction-free indicator of galaxy star-formation activity due to the redshifted PAH emission lines (6.2, 7.7, and 8.6 mu m). We show statistically that the cluster galaxies have a lower S-15 mu m/S-9 mu m flux ratio than do field galaxies, i.e., cluster galaxies already have lower star-formation activity at 0.9 < z < 1.7, pushing the fort-nation epoch of these galaxy clusters to a higher redshift.

Z-Spec([1,2,3,4,5,6]) is a cryogenic, broadband, millimeter-wave grating spectrometer. it is capable of obtaining many spectral lines simultaneously because of its unprecedented broad bandwidth (185-305GHz). The bandpass covers the 1 mm atmospheric transmission window with a resolving power of 250-400. Z-Spec uses 160 silicon nitride micromesh bolometers cooled down to less than 100mK for background-limited performance. The unique capability of Z-Spec to detect multiple lines Simultaneously allows us to obtain information efficiently on the physical and chemical conditions of nearby Ultra-luminous Infrared Galaxies (ULIRGs) powered by starbursts or Active Galactic Nuclei. Here we report on new millimeter-wave broadband data for ULIRGs acquired with Z-Spec and the noise performance and achieved sensitivity in observations with the CSO. We found that during the observations the noise scales with the atmospheric opacity and can be explained well by our sensitivity model, considering the photon noise originating from the sky and the telescope, as well as the detector and electronics noise. The photon noise is found to dominate the total noise.

We present the recent results of millimeter-wave spectroscopic observations of dusty (U)LIRGs which harbor AGN and/or obscured starburst cores. We then discuss the nature of (U)LIRGs by comparing with the near and mid-infrared spectra available so far which are taken with Spitzer and AKARI. In this study, we use 1-1.5mm spectra obtained with Z-Spec's, which is a millimeter broadband spectrometer covering 1mm atmospheric transmission window with a resolving power of 250- 350. It has 160 silicon nitride micro-mesh bolometers constructed in array and are cooled down below 100mK to achieve the background limited performance. This wide bandwidth make it possible to detect multiple lines at once and to do unbiased line surveys. It has been installed at Caltech Submillimeter Observatory (CSO) at Mauna Kea. Thanks to its compact size, lighttight, no moving parts and so on; it is an ideal candidate for future far-infrared spectrometer on board a cold telescope in space (e.g. BLISS on SPICA, Bradford et al.). In the present work, by using this unique Z-Spec features, we aim to investigate the nature of dusty (U)LIRGs, which are very luminous in infrared (Lir > 1012 Lsun ). Since energetic cores in the center of the (U)LIRGs are thought to be buried within the thick dust and thus not easy to be observed at optical, observation at longer wavelength is essential to study them. Z-Spec can detect millimeter-wave emission lines without suffering from the dust obscuration, such as 12 CO, 13 CO, HCO+ , HCN, HNC, CS which trace molecular gas, and the continuum emission from thermal dust emission at higher frequencies and the free-free emission at lower frequencies. Also AKARI and Spitzer are capable of observing the nearand mid-infrared spectral features in absorption (9.7µm Silicate dust, 3.4µm Carbonaceous dust, H2 O, CO) or PAH emissions. We will also examine the relation between the infrared and millimeter-wave spectral aspects from the present data taken with Z-Spec, AKARI and Spitzer. Comparison of these results may lead us to obtain a new diagnostic tool to understand dusty (U)LIRGs....

We present the results of optical identifications for 257 mid-infrared sources detected with a deep 15K_{s}... / We present the results of optical identifications for 257 mid-infrared sources detected with a deep 15 Am survey over approximately 80 arcmin(2) area in the AKARI performance verification field near the North Ecliptic Pole. The 15 mu m fluxes of the sources range from 1 mJy down to 40 mu Jy, approximately one half of which are below 100 mu Jy. Optical counterparts were searched for within a 2 ''-3 '' radius in both the BVRi'z' catalog generated by using the deep Subaru/Suprime-cam field, which covers one-third of the performance verification field, and the g'r'i'z' catalog based on observations made with MegaCam at CFHT. We found that the B - R and R - z' colors of sources with successful optical identifications are systematically redder than that of the entire optical sample in the same field. Moreover, approximately 40% of the 15 mu m sources show colors with R - L15 > 5, which cannot be explained by the spectral energy distribution (SED) of normal quiescent spiral galaxies, but are consistent with SEDs of redshifted (z > 1) starburst or ultraluminous infrared galaxies. This result indicates that the fraction of the ultraluminous infrared galaxies in our faint 15 mu m sample is much larger than that in our brighter 15 mu m sources, which is consistent with the evolving mid-infrared luminosity function derived by recent studies based on Spitzer 24 Am deep surveys. Based on an SED fitting technique, the nature of the faint 15 Am sources is further discussed for a selected number of sources with available K-s-band data.

We present the results of optical identifications for 257 mid-infrared sources detected with a deep 15 Am survey over approximately 80 arcmin(2) area in the AKARI performance verification field near the North Ecliptic Pole. The 15 mu m fluxes of the sources range from 1 mJy down to 40 mu Jy, approximately one half of which are below 100 mu Jy. Optical counterparts were searched for within a 2 ''-3 '' radius in both the BVRi'z' catalog generated by using the deep Subaru/Suprime-cam field, which covers one-third of the performance verification field, and the g'r'i'z' catalog based on observations made with MegaCam at CFHT. We found that the B - R and R - z' colors of sources with successful optical identifications are systematically redder than that of the entire optical sample in the same field. Moreover, approximately 40% of the 15 mu m sources show colors with R - L15 > 5, which cannot be explained by the spectral energy distribution (SED) of normal quiescent spiral galaxies, but are consistent with SEDs of redshifted (z > 1) starburst or ultraluminous infrared galaxies. This result indicates that the fraction of the ultraluminous infrared galaxies in our faint 15 mu m sample is much larger than that in our brighter 15 mu m sources, which is consistent with the evolving mid-infrared luminosity function derived by recent studies based on Spitzer 24 Am deep surveys. Based on an SED fitting technique, the nature of the faint 15 Am sources is further discussed for a selected number of sources with available K-s-band data.