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© 2011. The American Astronomical Society. All rights reserved. Artículo firmado por 24 autores. The authors thank the entire S^4G team for their efforts in this project. This work is based on observations and archival data made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. We are grateful to the dedicated staff at the Spitzer Science Center for their help and support in planning and execution of this Exploration Science program. We also gratefully acknowledge support from NASA JPL/Spitzer grant RSA 1374189 provided for the S^(4)G project.K.S., J.-C.M.M., T. Kim and T. Mizusawa acknowledge support from the National Radio Astronomy Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. E. A. and A. B. thank the Centre National d'Etudes Spatiales for financial support. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is http://www.sdss.org/. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration., Most, if not all, disk galaxies have a thin (classical) disk and a thick disk. In most models thick disks are thought to be a necessary consequence of the disk formation and/or evolution of the galaxy. We present the results of a study of the thick disk properties in a sample of carefully selected edge-on galaxies with types ranging from T = 3 to T = 8. We fitted one-dimensional luminosity profiles with physically motivated functions—the solutions of two stellar and one gaseous isothermal coupled disks in equilibrium—which are likely to yield more accurate results than other functions used in previous studies. The images used for the fits come from the Spitzer Survey of Stellar Structure in Galaxies (S^4G). We found that thick disks are on average more massive than previously reported, mostly due to the selected fitting function. Typically, the thin and thick disks have similar masses. We also found that thick disks do not flare significantly within the observed range in galactocentric radii and that the ratio of thick-to-thin disk scale heights is higher for galaxies of earlier types. Our results tend to favor an in situ origin for most of the stars in the thick disk. In addition, the thick disk may contain a significant amount of stars coming from satellites accreted after the initial buildup of the galaxy and an extra fraction of stars coming from the secular heating of the thin disk by its own overdensities. Assigning thick disk light to the thin disk component may lead to an underestimate of the overall stellar mass in galaxies because of different mass-to-light ratios in the two disk components. On the basis of our new results, we estimate that disk stellar masses are between 10% and 50% higher than previously thought and we suggest that thick disks are a reservoir of "local missing baryons.", National Radio Astronomy Observatory, Centre National d'Etudes Spatiales, Alfred P. Sloan Foundation, National Science Foundation (NFS), EE.UU., U.S. Department of Energy, National Aeronautics and Space Administration (NASA), Japanese Monbukagakusho, Max Planck Society, Higher Education Funding Council for England, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Detailed observations of star-forming galaxies at high redshift are critical to understanding the formation and evolution of the earliest galaxies. Gravitational lensing provides an important boost, allowing observations at physical scales unreachable in unlensed galaxies. We present three lensed galaxies from the RELICS survey at z (phot) = 6-10, including the most highly magnified galaxy at z (phot) similar to 6 (WHL 0137-zD1, dubbed the Sunrise Arc), the brightest known lensed galaxy at z (phot) similar to 6 (MACS 0308-zD1), and the only spatially resolved galaxy currently known at z (phot) similar to 10 (SPT 0615-JD). The Sunrise Arc contains seven star-forming clumps with delensed radii as small as 3 pc, the smallest spatial scales yet observed in a z > 6 galaxy, while SPT 0615-JD contains features measuring a few tens of parsecs. MACS 0308-zD1 contains an r similar to 30 pc clump with a star formation rate (SFR) of similar to 3 M (circle dot) yr(-1), giving it an SFR surface density of sigma(SFR) similar to 10(3) M (circle dot) yr(-1) kpc(-2). These galaxies provide a unique window into small-scale star formation during the epoch of reionization. They will be excellent targets for future observations with JWST, including one approved program targeting the Sunrise Arc.

Detailed observations of star-forming galaxies at high redshift are critical to understanding the formation and evolution of the earliest galaxies. Gravitational lensing provides an important boost, allowing observations at physical scales unreachable in unlensed galaxies. We present three lensed galaxies from the RELICS survey at z (phot) = 6-10, including the most highly magnified galaxy at z (phot) similar to 6 (WHL 0137-zD1, dubbed the Sunrise Arc), the brightest known lensed galaxy at z (phot) similar to 6 (MACS 0308-zD1), and the only spatially resolved galaxy currently known at z (phot) similar to 10 (SPT 0615-JD). The Sunrise Arc contains seven star-forming clumps with delensed radii as small as 3 pc, the smallest spatial scales yet observed in a z > 6 galaxy, while SPT 0615-JD contains features measuring a few tens of parsecs. MACS 0308-zD1 contains an r similar to 30 pc clump with a star formation rate (SFR) of similar to 3 M (circle dot) yr(-1), giving it an SFR surface density of sigma(SFR) similar to 10(3) M (circle dot) yr(-1) kpc(-2). These galaxies provide a unique window into small-scale star formation during the epoch of reionization. They will be excellent targets for future observations with JWST, including one approved program targeting the Sunrise Arc.

We report the serendipitous discovery of an overdensity of CO emitters in an X-ray-identified cluster (Log(10)M(halo)/M-circle dot similar to 13.6 at z = 1.3188) using ALMA. We present spectroscopic confirmation of six new cluster members exhibiting CO(2-1) emission, adding to two existing optical/IR spectroscopic members undetected in CO. This is the lowest-mass cluster to date at z > 1 with molecular gas measurements, bridging the observational gap between galaxies in the more extreme, well-studied clusters (Log(10) M-halo/M-circle dot greater than or similar to 14) and those in group or field environments at cosmic noon. The CO sources are concentrated on the sky (within similar to 1 arcmin diameter) and phase space analysis indicates the gas resides in galaxies already within the cluster environment. We find that CO sources sit in similar phase space as CO-rich galaxies in more massive clusters at similar redshifts (have similar accretion histories) while maintaining field-like molecular gas reservoirs, compared to scaling relations. This work presents the deepest CO survey to date in a galaxy cluster at z > 1, uncovering gas reservoirs down to M-H2 > 1.6 x 10(10)M(circle dot) (5a at 50% primary beam). Our deep limits rule out the presence of gas content in excess of the field scaling relations; however, combined with literature CO detections, cluster gas fractions in general appear systematically high, on the upper envelope or above the field. This study is the first demonstration that low-mass clusters at z similar to 1-2 can host overdensities of CO emitters with surviving gas reservoirs, in line with the prediction that quenching is delayed after first infall while galaxies consume the gas bound to the disk.

We report 18 dust continuum detections (>= 3.3 sigma) at similar to 88 and 158 mu m out of 49 ultraviolet (UV)-bright galaxies (M-UV < -21.3 mag) at z > 6.5, observed by the Cycle-7 Atacama Large Millimeter/submillimeter Array (ALMA) Large Program, Reionization-Era Bright Emission Line Survey (REBELS) and its pilot programs. This has more than tripled the number of dust continuum detections known at z > 6.5. Out of these 18 detections, 12 are reported for the first time as part of REBELS. In addition, 15 of the dust continuum detected galaxies also show a [C II](158 mu m) emission line, providing us with accurate redshifts. We anticipate more line emission detections from six targets (including three continuum detected targets) where observations are still ongoing. We estimate that all of the sources have an infrared (IR) luminosity (L IR) in a range of 3-8 x10(11) L-circle dot. except for one with L-IR = 1.5(-0.5)(+0.8) x10(12) L-circle dot. Their fraction of obscured star formation is significant at greater than or similar to 50 per cent, despite being UV-selected galaxies. Some of the dust continuum detected galaxies show spatial offsets (similar to 0.5-1.5 arcsec) between the rest-UV and far-IR emission peaks. These separations could imply spatially decoupled phases of obscured and unobscured star formation, but a higher spatial resolution observation is required to confirm this. REBELS offers the best available statistical constraints on obscured star formation in UV-luminous galaxies at z > 6.5.

We measure, for the first time, the median equivalent width (EW) of H alpha+[N II] in star-forming galaxies at z similar to 8. Our estimate leverages the unique photometric depth of the Spitzer/IRAC 5.8 mu m band mosaics (probing approximate to 5500-7100 angstrom at z similar to 8) of the GOODS Reionization Era Wide Area Treasury from Spitzer (GREATS) program. We median-stacked the stamps of 102 Lyman-break galaxies in the 3.6, 4.5, 5.8, and 8.0 mu m bands, after carefully removing potential contamination from neighboring sources. We infer an extreme rest-frame EW0(H alpha+[N II]) = 2328(-1127)(+1326) angstrom from the measured red [3.6] - [5.8] = 0.82 +/- 0.27 mag, consistent with young (less than or similar to 10(7) yr) average stellar population ages at z similar to 8. This implies an ionizing photon production efficiency of log(xi(ion,0)/erg Hz(-1)) = 25.97(-0.28)(+0.18). Such a high value for photoproduction, similar to the highest values found at z less than or similar to 4, indicates that only modest escape fractions f(esc) less than or similar to 0.3 (at 2 sigma) are sufficient for galaxies brighter than M-UV < -18 mag to reionize the neutral hydrogen at z similar to 8. This requirement is relaxed even more to f(esc)

We report the serendipitous discovery of an overdensity of CO emitters in an X-ray-identified cluster (Log(10)M(halo)/M-circle dot similar to 13.6 at z = 1.3188) using ALMA. We present spectroscopic confirmation of six new cluster members exhibiting CO(2-1) emission, adding to two existing optical/IR spectroscopic members undetected in CO. This is the lowest-mass cluster to date at z > 1 with molecular gas measurements, bridging the observational gap between galaxies in the more extreme, well-studied clusters (Log(10) M-halo/M-circle dot greater than or similar to 14) and those in group or field environments at cosmic noon. The CO sources are concentrated on the sky (within similar to 1 arcmin diameter) and phase space analysis indicates the gas resides in galaxies already within the cluster environment. We find that CO sources sit in similar phase space as CO-rich galaxies in more massive clusters at similar redshifts (have similar accretion histories) while maintaining field-like molecular gas reservoirs, compared to scaling relations. This work presents the deepest CO survey to date in a galaxy cluster at z > 1, uncovering gas reservoirs down to M-H2 > 1.6 x 10(10)M(circle dot) (5a at 50% primary beam). Our deep limits rule out the presence of gas content in excess of the field scaling relations; however, combined with literature CO detections, cluster gas fractions in general appear systematically high, on the upper envelope or above the field. This study is the first demonstration that low-mass clusters at z similar to 1-2 can host overdensities of CO emitters with surviving gas reservoirs, in line with the prediction that quenching is delayed after first infall while galaxies consume the gas bound to the disk.

We measure, for the first time, the median equivalent width (EW) of H alpha+[N II] in star-forming galaxies at z similar to 8. Our estimate leverages the unique photometric depth of the Spitzer/IRAC 5.8 mu m band mosaics (probing approximate to 5500-7100 angstrom at z similar to 8) of the GOODS Reionization Era Wide Area Treasury from Spitzer (GREATS) program. We median-stacked the stamps of 102 Lyman-break galaxies in the 3.6, 4.5, 5.8, and 8.0 mu m bands, after carefully removing potential contamination from neighboring sources. We infer an extreme rest-frame EW0(H alpha+[N II]) = 2328(-1127)(+1326) angstrom from the measured red [3.6] - [5.8] = 0.82 +/- 0.27 mag, consistent with young (less than or similar to 10(7) yr) average stellar population ages at z similar to 8. This implies an ionizing photon production efficiency of log(xi(ion,0)/erg Hz(-1)) = 25.97(-0.28)(+0.18). Such a high value for photoproduction, similar to the highest values found at z less than or similar to 4, indicates that only modest escape fractions f(esc) less than or similar to 0.3 (at 2 sigma) are sufficient for galaxies brighter than M-UV < -18 mag to reionize the neutral hydrogen at z similar to 8. This requirement is relaxed even more to f(esc)

We report 18 dust continuum detections (>= 3.3 sigma) at similar to 88 and 158 mu m out of 49 ultraviolet (UV)-bright galaxies (M-UV < -21.3 mag) at z > 6.5, observed by the Cycle-7 Atacama Large Millimeter/submillimeter Array (ALMA) Large Program, Reionization-Era Bright Emission Line Survey (REBELS) and its pilot programs. This has more than tripled the number of dust continuum detections known at z > 6.5. Out of these 18 detections, 12 are reported for the first time as part of REBELS. In addition, 15 of the dust continuum detected galaxies also show a [C II](158 mu m) emission line, providing us with accurate redshifts. We anticipate more line emission detections from six targets (including three continuum detected targets) where observations are still ongoing. We estimate that all of the sources have an infrared (IR) luminosity (L IR) in a range of 3-8 x10(11) L-circle dot. except for one with L-IR = 1.5(-0.5)(+0.8) x10(12) L-circle dot. Their fraction of obscured star formation is significant at greater than or similar to 50 per cent, despite being UV-selected galaxies. Some of the dust continuum detected galaxies show spatial offsets (similar to 0.5-1.5 arcsec) between the rest-UV and far-IR emission peaks. These separations could imply spatially decoupled phases of obscured and unobscured star formation, but a higher spatial resolution observation is required to confirm this. REBELS offers the best available statistical constraints on obscured star formation in UV-luminous galaxies at z > 6.5.

While emission-selected galaxy surveys are biased towards the most luminous part of the galaxy population, absorption selection is a potentially unbiased galaxy selection technique with respect to luminosity. However, the physical properties of absorption-selected galaxies are not well characterized. Here, we study the excitation conditions in the interstellar medium (ISM) in damped Ly alpha (DLA) absorption-selected galaxies. We present a study of the CO spectral-line energy distribution (SLED) in four high-metallicity absorption-selected galaxies with previously reported CO detections at intermediate (z similar to 0.7) and high (z similar to 2) redshifts. We find further evidence for a wide variety of ISM conditions in these galaxies. Two out of the four galaxies show CO SLEDs consistent with that of the Milky Way inner disc. Interestingly, one of these galaxies is at z similar to 2 and has a CO SLED below that of main-sequence galaxies at similar redshifts. The other two galaxies at z > 2 show more excited ISM conditions, with one of them showing thermal excitation of the mid-J (J = 3, 4) levels, similar to that seen in two massive main-sequence galaxies at these redshifts. Overall, we find that absorption selection traces a diverse population of galaxies.

While emission-selected galaxy surveys are biased towards the most luminous part of the galaxy population, absorption selection is a potentially unbiased galaxy selection technique with respect to luminosity. However, the physical properties of absorption-selected galaxies are not well characterized. Here, we study the excitation conditions in the interstellar medium (ISM) in damped Ly alpha (DLA) absorption-selected galaxies. We present a study of the CO spectral-line energy distribution (SLED) in four high-metallicity absorption-selected galaxies with previously reported CO detections at intermediate (z similar to 0.7) and high (z similar to 2) redshifts. We find further evidence for a wide variety of ISM conditions in these galaxies. Two out of the four galaxies show CO SLEDs consistent with that of the Milky Way inner disc. Interestingly, one of these galaxies is at z similar to 2 and has a CO SLED below that of main-sequence galaxies at similar redshifts. The other two galaxies at z > 2 show more excited ISM conditions, with one of them showing thermal excitation of the mid-J (J = 3, 4) levels, similar to that seen in two massive main-sequence galaxies at these redshifts. Overall, we find that absorption selection traces a diverse population of galaxies.

Deep rest-optical observations are required to accurately constrain the stellar populations of z similar to 8 galaxies. Due to significant limitations in the availability of such data for statistically complete samples, observational results have been limited to modest numbers of bright or lensed sources. To revolutionize the present characterization of z similar to 8 galaxies, we exploit the ultradeep (similar to 27 mag, 3 sigma) Spitzer/Infrared Array Camera (IRAC) 3.6 and 4.5 mu m data, probing the rest-frame optical at z similar to 8, over similar to 200 arcmin(2) of the GOODS fields from the recently completed GOODS Re-ionization Era wide-Area Treasury from Spitzer program (GREATS), combined with observations in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)/Ultra Deep Survey (UDS) and CANDELS/Cosmic Evolution Survey (COSMOS) fields. We stacked greater than or similar to 100 z similar to 8 Lyman-break galaxies in four bins of UV luminosity (M (UV) similar to -20.7 to -18.4 mag) and study their H (160) - [3.6] and [3.6]-[4.5] colors. We find young ages (less than or similar to 100 Myr) for the three faintest stacks, inferred from their blue H (160) - [3.6] similar to 0 mag colors, consistent with a negative Balmer break. Meanwhile, the redder H (160) - [3.6] color seen in the brightest stack is suggestive of slightly older ages. We explored the existence of a correlation between the UV luminosity and age, and find either no trend or fainter galaxies being younger. The stacked SEDs also exhibit very red [3.6]-[4.5] similar to 0.5 mag colors, indicative of intense [O iii]+H beta nebular emission and star formation rate (SFR). The correspondingly high specific SFRs, sSFR greater than or similar to 10 Gyr(-1), are consistent with recent determinations at similar redshifts and higher luminosities, and support the coevolution between the sSFR and the specific halo mass accretion rate.

We present results from Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm continuum observations of a sample of 27 star-forming galaxies at z = 2.1-2.5 from the MOSFIRE Deep Evolution Field survey with metallicity and star formation rate measurements from optical emission lines. Using stacks of Spitzer, Herschel, and ALMA photometry (rest frame similar to 8-400 mu m), we examine the infrared (IR) spectral energy distributions (SED) of z similar to 2.3 subsolar-metallicity (similar to 0.5 Z (circle dot)) luminous infrared galaxies (LIRGs). We find that the data agree well with an average template of higher-luminosity local low-metallicity dwarf galaxies (reduced chi (2) = 1.8). When compared with the commonly used templates for solar-metallicity local galaxies or high-redshift LIRGs and ultraluminous IR galaxies, even in the most favorable case (with reduced chi (2) = 2.8), the templates are rejected at >98% confidence. The broader and hotter IR SED of both the local dwarfs and high-redshift subsolar-metallicity galaxies may result from different grain properties or a harder/more intense ionizing radiation field that increases the dust temperature. The obscured star formation rate (SFR) indicated by the far-IR emission of the subsolar-metallicity galaxies is only similar to 60% of the total SFR, considerably lower than that of the local LIRGs with similar to 96%-97% obscured fractions. Due to the evolving IR SED shape, the local LIRG templates fit to mid-IR data overestimate the Rayleigh-Jeans tail measurements by a factor of 2-20. These templates underestimate IR luminosities if fit to the observed ALMA fluxes by >0.4 dex. At a given stellar mass or metallicity, dust masses at z similar to 2.3 are an order of magnitude higher than z similar to 0. Given the predicted molecular gas fractions, the observed z similar to 2.3 dust-to-stellar mass ratios suggest lower dust-to-molecular gas masses than in local galaxies with similar metallicities.

Deep rest-optical observations are required to accurately constrain the stellar populations of z similar to 8 galaxies. Due to significant limitations in the availability of such data for statistically complete samples, observational results have been limited to modest numbers of bright or lensed sources. To revolutionize the present characterization of z similar to 8 galaxies, we exploit the ultradeep (similar to 27 mag, 3 sigma) Spitzer/Infrared Array Camera (IRAC) 3.6 and 4.5 mu m data, probing the rest-frame optical at z similar to 8, over similar to 200 arcmin(2) of the GOODS fields from the recently completed GOODS Re-ionization Era wide-Area Treasury from Spitzer program (GREATS), combined with observations in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)/Ultra Deep Survey (UDS) and CANDELS/Cosmic Evolution Survey (COSMOS) fields. We stacked greater than or similar to 100 z similar to 8 Lyman-break galaxies in four bins of UV luminosity (M (UV) similar to -20.7 to -18.4 mag) and study their H (160) - [3.6] and [3.6]-[4.5] colors. We find young ages (less than or similar to 100 Myr) for the three faintest stacks, inferred from their blue H (160) - [3.6] similar to 0 mag colors, consistent with a negative Balmer break. Meanwhile, the redder H (160) - [3.6] color seen in the brightest stack is suggestive of slightly older ages. We explored the existence of a correlation between the UV luminosity and age, and find either no trend or fainter galaxies being younger. The stacked SEDs also exhibit very red [3.6]-[4.5] similar to 0.5 mag colors, indicative of intense [O iii]+H beta nebular emission and star formation rate (SFR). The correspondingly high specific SFRs, sSFR greater than or similar to 10 Gyr(-1), are consistent with recent determinations at similar redshifts and higher luminosities, and support the coevolution between the sSFR and the specific halo mass accretion rate.

We present results from Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm continuum observations of a sample of 27 star-forming galaxies at z = 2.1-2.5 from the MOSFIRE Deep Evolution Field survey with metallicity and star formation rate measurements from optical emission lines. Using stacks of Spitzer, Herschel, and ALMA photometry (rest frame similar to 8-400 mu m), we examine the infrared (IR) spectral energy distributions (SED) of z similar to 2.3 subsolar-metallicity (similar to 0.5 Z (circle dot)) luminous infrared galaxies (LIRGs). We find that the data agree well with an average template of higher-luminosity local low-metallicity dwarf galaxies (reduced chi (2) = 1.8). When compared with the commonly used templates for solar-metallicity local galaxies or high-redshift LIRGs and ultraluminous IR galaxies, even in the most favorable case (with reduced chi (2) = 2.8), the templates are rejected at >98% confidence. The broader and hotter IR SED of both the local dwarfs and high-redshift subsolar-metallicity galaxies may result from different grain properties or a harder/more intense ionizing radiation field that increases the dust temperature. The obscured star formation rate (SFR) indicated by the far-IR emission of the subsolar-metallicity galaxies is only similar to 60% of the total SFR, considerably lower than that of the local LIRGs with similar to 96%-97% obscured fractions. Due to the evolving IR SED shape, the local LIRG templates fit to mid-IR data overestimate the Rayleigh-Jeans tail measurements by a factor of 2-20. These templates underestimate IR luminosities if fit to the observed ALMA fluxes by >0.4 dex. At a given stellar mass or metallicity, dust masses at z similar to 2.3 are an order of magnitude higher than z similar to 0. Given the predicted molecular gas fractions, the observed z similar to 2.3 dust-to-stellar mass ratios suggest lower dust-to-molecular gas masses than in local galaxies with similar metallicities.

Giant star-forming regions (clumps) are widespread features of galaxies at z approximate to 1-4. Theory predicts that they can play a crucial role in galaxy evolution, if they survive to stellar feedback for >50 Myr. Numerical simulations show that clumps' survival depends on the stellar feedback recipes that are adopted. Up to date, observational constraints on both clumps' outflows strength and gas removal time-scale are still uncertain. In this context, we study a line-emitting galaxy at redshift z similar or equal to 3.4 lensed by the foreground galaxy cluster Abell 2895. Four compact clumps with sizes less than or similar to 280 pc and representative of the low-mass end of clumps' mass distribution (stellar masses less than or similar to 2 x 10(8) M-circle dot) dominate the galaxy morphology. The clumps are likely forming stars in a starbursting mode and have a young stellar population (similar to 10 Myr). The properties of the Lyman-alpha (Ly alpha) emission and nebular far-ultraviolet absorption lines indicate the presence of ejected material with global outflowing velocities of similar to 200-300 km s(-1). Assuming that the detected outflows are the consequence of star formation feedback, we infer an average mass loading factor (eta) for the clumps of similar to 1.8-2.4 consistent with results obtained from hydrodynamical simulations of clumpy galaxies that assume relatively strong stellar feedback. Assuming no gas inflows (semiclosed box model), the estimates of n suggest that the time-scale over which the outflows expel the molecular gas reservoir (similar or equal to 7 x 10(8 )M(circle dot)) of the four detected low-mass clumps is less than or similar to 50 Myr.

We present the deepest Spitzer/InfraRed Array Camera (IRAC) 3.6, 4.5, 5.8, and 8.0 mu m wide-area mosaics yet over the Great Observatories Origins Deep Survey (GOODS)-N and GOODS-S fields as part of the GOODS Reionization Era wide-Area Treasury from Spitzer (GREATS) project. We reduced and mosaicked in a self-consistent way observations taken by the 11 different Spitzer/IRAC programs over the two GOODS fields from 12 yr of Spitzer cryogenic and warm-mission data. The cumulative depth in the 3.6 mu m and 4.5 mu m bands amounts to similar to 4260 hr, similar to 1220 hr of which are new very deep observations from the GREATS program itself. In the deepest area, the full-depth mosaics reach greater than or similar to 200 hr over an area of similar to 100 arcmin(2), corresponding to a sensitivity of similar to 29 AB magnitude at 3.6 mu m (1 sigma for point sources). Archival cryogenic 5.8 mu m and 8.0 mu m band data (a cumulative 976 hr) are also included in the release. The mosaics are projected onto the tangential plane of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/GOODS at a 0.'' 3 pixel(-1) scale. This paper describes the methodology enabling, and the characteristics of, the public release of the mosaic science images, the corresponding coverage maps in the four IRAC bands, and the empirical point-spread functions (PSFs). These PSFs enable mitigation of the source blending effects by taking into account the complex position-dependent variation in the IRAC images. The GREATS data products are in the Infrared Science Archive. We also release the deblended 3.6-8.0 mu m photometry 9192 Lyman-break galaxies at z similar to 3.5-10. GREATS will be the deepest mid-infrared imaging until the James Webb Space Telescope and, as such, constitutes a major resource for characterizing early galaxy assembly.

Giant star-forming regions (clumps) are widespread features of galaxies at z approximate to 1-4. Theory predicts that they can play a crucial role in galaxy evolution, if they survive to stellar feedback for >50 Myr. Numerical simulations show that clumps' survival depends on the stellar feedback recipes that are adopted. Up to date, observational constraints on both clumps' outflows strength and gas removal time-scale are still uncertain. In this context, we study a line-emitting galaxy at redshift z similar or equal to 3.4 lensed by the foreground galaxy cluster Abell 2895. Four compact clumps with sizes less than or similar to 280 pc and representative of the low-mass end of clumps' mass distribution (stellar masses less than or similar to 2 x 10(8) M-circle dot) dominate the galaxy morphology. The clumps are likely forming stars in a starbursting mode and have a young stellar population (similar to 10 Myr). The properties of the Lyman-alpha (Ly alpha) emission and nebular far-ultraviolet absorption lines indicate the presence of ejected material with global outflowing velocities of similar to 200-300 km s(-1). Assuming that the detected outflows are the consequence of star formation feedback, we infer an average mass loading factor (eta) for the clumps of similar to 1.8-2.4 consistent with results obtained from hydrodynamical simulations of clumpy galaxies that assume relatively strong stellar feedback. Assuming no gas inflows (semiclosed box model), the estimates of n suggest that the time-scale over which the outflows expel the molecular gas reservoir (similar or equal to 7 x 10(8 )M(circle dot)) of the four detected low-mass clumps is less than or similar to 50 Myr.

Star formation rate (SFR) measurements at z>4 have relied mostly on the rest-frame far-ultraviolet (FUV) observations. The corrections for dust attenuation based on the IRX-beta relation are highly uncertain and are still debated in the literature. Hence, rest-frame far-infrared (FIR) observations are necessary to constrain the dust-obscured component of the SFR. In this paper, we exploit the rest-frame FIR continuum observations collected by the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) to directly constrain the obscured SFR in galaxies at 4.4

Using a large sample of sub-L-* galaxies, with similar UV magnitudes, M-UV similar or equal to -19 at z similar or equal to 6, extracted from the FirstLight simulations, we show the diversity of galaxies at the end of the reionization epoch. We find a factor similar to 40 variation in the specific star formation rate (sSFR). This drives a similar to 1 dex range in equivalent width of the [O III]lambda 5007 line. Variations in nebular metallicity and ionization parameter within H II regions lead to a scatter in the equivalent widths and [O III]/H alpha line ratio at a fixed sSFR. [O III]-bright ([O III]/H alpha>1) emitters have higher ionization parameters and/or higher metallicities than H alpha-bright ([O III]/H alpha

The relation between infrared excess (IRX) and UV spectral slope (beta(UV)) is an empirical probe of dust properties of galaxies. The shape, scatter, and redshift evolution of this relation are not well understood, however, leading to uncertainties in estimating the dust content and star formation rates (SFRs) of galaxies at high redshift. In this study, we explore the nature and properties of the IRX-beta(UV) relation with a sample of z = 2-6 galaxies (M-* approximate to 10(9)-10(12) M-circle dot) extracted from high-resolution cosmological simulations (MassiveFIRE) of the Feedback in Realistic Environments (FIRE) project. The galaxies in our sample show an IRX-beta(UV) relation that is in good agreement with the observed relation in nearby galaxies. IRX is tightly coupled to the UV optical depth, and is mainly determined by the dust-to-star geometry instead of total dust mass, while beta(UV) is set both by stellar properties, UV optical depth, and the dust extinction law. Overall, much of the scatter in the IRX-beta(UV) relation of our sample is found to be driven by variations of the intrinsic UV spectral slope. We further assess how the IRX-beta(UV) relation depends on viewing direction, dust-to-metal ratio, birth-cloud structures, and the dust extinction law and we present a simple model that encapsulates most of the found dependencies. Consequently, we argue that the reported 'deficit' of the infrared/sub-millimetre bright objects at z greater than or similar to 5 does not necessarily imply a non-standard dust extinction law at those epochs.

Giant star-forming regions (clumps) are widespread features of galaxies at z approximate to 1-4. Theory predicts that they can play a crucial role in galaxy evolution, if they survive to stellar feedback for >50 Myr. Numerical simulations show that clumps' survival depends on the stellar feedback recipes that are adopted. Up to date, observational constraints on both clumps' outflows strength and gas removal time-scale are still uncertain. In this context, we study a line-emitting galaxy at redshift z similar or equal to 3.4 lensed by the foreground galaxy cluster Abell 2895. Four compact clumps with sizes less than or similar to 280 pc and representative of the low-mass end of clumps' mass distribution (stellar masses less than or similar to 2 x 10(8) M-circle dot) dominate the galaxy morphology. The clumps are likely forming stars in a starbursting mode and have a young stellar population (similar to 10 Myr). The properties of the Lyman-alpha (Ly alpha) emission and nebular far-ultraviolet absorption lines indicate the presence of ejected material with global outflowing velocities of similar to 200-300 km s(-1). Assuming that the detected outflows are the consequence of star formation feedback, we infer an average mass loading factor (eta) for the clumps of similar to 1.8-2.4 consistent with results obtained from hydrodynamical simulations of clumpy galaxies that assume relatively strong stellar feedback. Assuming no gas inflows (semiclosed box model), the estimates of n suggest that the time-scale over which the outflows expel the molecular gas reservoir (similar or equal to 7 x 10(8 )M(circle dot)) of the four detected low-mass clumps is less than or similar to 50 Myr.

Star formation rate (SFR) measurements at z>4 have relied mostly on the rest-frame far-ultraviolet (FUV) observations. The corrections for dust attenuation based on the IRX-beta relation are highly uncertain and are still debated in the literature. Hence, rest-frame far-infrared (FIR) observations are necessary to constrain the dust-obscured component of the SFR. In this paper, we exploit the rest-frame FIR continuum observations collected by the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) to directly constrain the obscured SFR in galaxies at 4.4

Using a large sample of sub-L-* galaxies, with similar UV magnitudes, M-UV similar or equal to -19 at z similar or equal to 6, extracted from the FirstLight simulations, we show the diversity of galaxies at the end of the reionization epoch. We find a factor similar to 40 variation in the specific star formation rate (sSFR). This drives a similar to 1 dex range in equivalent width of the [O III]lambda 5007 line. Variations in nebular metallicity and ionization parameter within H II regions lead to a scatter in the equivalent widths and [O III]/H alpha line ratio at a fixed sSFR. [O III]-bright ([O III]/H alpha>1) emitters have higher ionization parameters and/or higher metallicities than H alpha-bright ([O III]/H alpha

The relation between infrared excess (IRX) and UV spectral slope (beta(UV)) is an empirical probe of dust properties of galaxies. The shape, scatter, and redshift evolution of this relation are not well understood, however, leading to uncertainties in estimating the dust content and star formation rates (SFRs) of galaxies at high redshift. In this study, we explore the nature and properties of the IRX-beta(UV) relation with a sample of z = 2-6 galaxies (M-* approximate to 10(9)-10(12) M-circle dot) extracted from high-resolution cosmological simulations (MassiveFIRE) of the Feedback in Realistic Environments (FIRE) project. The galaxies in our sample show an IRX-beta(UV) relation that is in good agreement with the observed relation in nearby galaxies. IRX is tightly coupled to the UV optical depth, and is mainly determined by the dust-to-star geometry instead of total dust mass, while beta(UV) is set both by stellar properties, UV optical depth, and the dust extinction law. Overall, much of the scatter in the IRX-beta(UV) relation of our sample is found to be driven by variations of the intrinsic UV spectral slope. We further assess how the IRX-beta(UV) relation depends on viewing direction, dust-to-metal ratio, birth-cloud structures, and the dust extinction law and we present a simple model that encapsulates most of the found dependencies. Consequently, we argue that the reported 'deficit' of the infrared/sub-millimetre bright objects at z greater than or similar to 5 does not necessarily imply a non-standard dust extinction law at those epochs.

Using the deepest 1.2 mm continuum map to date in the Hubble Ultra Deep Field, which was obtained as part of the ALMA Spectroscopic Survey (ASPECS) large program, we measure the cosmic density of dust and implied gas (H-2+H i) mass in galaxies as a function of look-back time. We do so by stacking the contribution from all H-band selected galaxies above a given stellar mass in distinct redshift bins, M decreases down to 10(10) M, but this growth slows down toward lower stellar masses. This flattening implies that at our stellar mass-completeness limits (10(8) M and 10(8.9) M at z similar to 0.4 and z similar to 3), both quantities converge toward the total cosmic dust and gas mass densities in galaxies. The cosmic dust and gas mass densities increase at early cosmic time, peak around z similar to 2, and decrease by a factor similar to 4 and 7, when compared to the density of dust and molecular gas in the local universe, respectively. The contribution of quiescent galaxies (i.e., with little on-going star formation) to the cosmic dust and gas mass densities is minor (less than or similar to 10%). The redshift evolution of the cosmic gas mass density resembles that of the SFR density, as previously found by CO-based measurements. This confirms that galaxies have relatively constant star formation efficiencies (within a factor similar to 2) across cosmic time. Our results also imply that by z similar to 0, a large fraction (similar to 90%) of dust formed in galaxies across cosmic time has either been destroyed or ejected to the intergalactic medium.

We investigate the properties of a sample of 35 galaxies, detected with the Atacama Large Millimeter/Submillimeter Array (ALMA) at 1.1 mm in the GOODS-ALMA field (area of 69 arcmin(2), resolution = 0.60 '', rms similar or equal to 0.18 mJy beam(-1)). Using the ultraviolet-to-radio deep multiwavelength coverage of the GOODS-South field, we fit the spectral energy distributions of these galaxies to derive their key physical properties. The galaxies detected by ALMA are among the most massive at z = 2-4 (M-star,M- med = 8.5 x 10(10)M(circle dot)) and they are either starburst or located in the upper part of the galaxy star-forming main sequence. A significant portion of our galaxy population (similar to 40%), located at z similar to 2.5-3, exhibits abnormally low gas fractions. The sizes of these galaxies, measured with ALMA, are compatible with the trend between the rest-frame 5000 angstrom size and stellar mass observed for z similar to 2 elliptical galaxies, suggesting that they are building compact bulges. We show that there is a strong link between star formation surface density (at 1.1 mm) and gas depletion time: The more compact a galaxy's star-forming region is, the shorter its lifetime will be (without gas replenishment). The identified compact sources associated with relatively short depletion timescales (similar to 100 Myr) are the ideal candidates to be the progenitors of compact elliptical galaxies at z similar to 2.

We present a catalogue of 22 755 objects with slitless, optical, Hubble Space Telescope (HST) spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS). The data cover similar to 220 sq. arcmin to 7-orbit (similar to 10 ks) depth in 20 parallel pointings of the Advanced Camera for Survey's G800L grism. The fields are located 6 arcmin away from 10 massive galaxy clusters in the HFF and CLASH footprints. 13 of the fields have ancillary HST imaging from these or other programs to facilitate a large number of applications, from studying metal distributions at z similar to 0.5, to quasars at z similar to 4, to the star formation histories of hundreds of galaxies in between. The spectroscopic catalogue has a median redshift of = 0.60 with a median uncertainty of Delta z/(1+z) less than or similar to 2 per cent at F814W less than or similar to 23 AB. Robust continuum detections reach a magnitude fainter. The 5 sigma limiting line flux is f(lim) approximate to 5x10(-17) erg s(-1) cm(-2) and half of all sources have 50 per cent of pixels contaminated at less than or similar to 1 per cent. All sources have 1D and 2D spectra, line fluxes/uncertainties and identifications, redshift probability distributions, spectral models, and derived narrow-band emission-line maps from the Grism Redshift and Line Analysis tool (GRIZLI). We provide other basic sample characterizations, show data examples, and describe sources and potential investigations of interest. All data and products will be available online along with software to facilitate their use.

We present a catalog of 208 0.3 z <2.1 emission-line galaxies (ELGs) selected from 1D slitless spectroscopy obtained using Hubble's WFC3 G102 grism, as part of the Faint Infrared Grism Survey. We identify ELG candidates by searching for significant peaks in all continuum-subtracted G102 spectra and, where possible, confirm candidates by identifying consistent emission lines in other available spectra or with published spectroscopic redshifts. We provide derived emission-line fluxes and errors, redshifts, and equivalent widths for H alpha lambda 6563, [O iii] lambda lambda 4959, 5007, and [O ii] lambda 3727 emission lines, for ELGs down to AB(F105W) >28 and >10(-17) erg cm(-2) s(-1) line flux. We use the resulting line catalog to investigate a possible relationship between line emission and a galaxy's environment. We use seventh-nearest-neighbor distances to investigate the typical surroundings of ELGs compared to non-ELGs, and we find that [O iii] emitters are preferentially found at intermediate galaxy densities near galaxy groups. We characterize these ELGs in terms of the galaxy specific star formation rate (SFR) versus stellar mass and find no significant influence of environment on that relation. We calculate SFRs and find no dependence of SFR on local galaxy surface density for 0.3 z alpha emitters and for 0.8 z iii] emitters. We find similar rates of close-pair interaction between ELGs and non-ELGs. For galaxy surface densities sigma

We investigate the properties of a sample of 35 galaxies, detected with the Atacama Large Millimeter/Submillimeter Array (ALMA) at 1.1 mm in the GOODS-ALMA field (area of 69 arcmin(2), resolution = 0.60 '', rms similar or equal to 0.18 mJy beam(-1)). Using the ultraviolet-to-radio deep multiwavelength coverage of the GOODS-South field, we fit the spectral energy distributions of these galaxies to derive their key physical properties. The galaxies detected by ALMA are among the most massive at z = 2-4 (M-star,M- med = 8.5 x 10(10)M(circle dot)) and they are either starburst or located in the upper part of the galaxy star-forming main sequence. A significant portion of our galaxy population (similar to 40%), located at z similar to 2.5-3, exhibits abnormally low gas fractions. The sizes of these galaxies, measured with ALMA, are compatible with the trend between the rest-frame 5000 angstrom size and stellar mass observed for z similar to 2 elliptical galaxies, suggesting that they are building compact bulges. We show that there is a strong link between star formation surface density (at 1.1 mm) and gas depletion time: The more compact a galaxy's star-forming region is, the shorter its lifetime will be (without gas replenishment). The identified compact sources associated with relatively short depletion timescales (similar to 100 Myr) are the ideal candidates to be the progenitors of compact elliptical galaxies at z similar to 2.

We present a catalogue of 22 755 objects with slitless, optical, Hubble Space Telescope (HST) spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS). The data cover similar to 220 sq. arcmin to 7-orbit (similar to 10 ks) depth in 20 parallel pointings of the Advanced Camera for Survey's G800L grism. The fields are located 6 arcmin away from 10 massive galaxy clusters in the HFF and CLASH footprints. 13 of the fields have ancillary HST imaging from these or other programs to facilitate a large number of applications, from studying metal distributions at z similar to 0.5, to quasars at z similar to 4, to the star formation histories of hundreds of galaxies in between. The spectroscopic catalogue has a median redshift of = 0.60 with a median uncertainty of Delta z/(1+z) less than or similar to 2 per cent at F814W less than or similar to 23 AB. Robust continuum detections reach a magnitude fainter. The 5 sigma limiting line flux is f(lim) approximate to 5x10(-17) erg s(-1) cm(-2) and half of all sources have 50 per cent of pixels contaminated at less than or similar to 1 per cent. All sources have 1D and 2D spectra, line fluxes/uncertainties and identifications, redshift probability distributions, spectral models, and derived narrow-band emission-line maps from the Grism Redshift and Line Analysis tool (GRIZLI). We provide other basic sample characterizations, show data examples, and describe sources and potential investigations of interest. All data and products will be available online along with software to facilitate their use.

© 2018. The American Astronomical Society. All rights reserved. Artículo firmado por 23 autores. We would like to thank the anonymous referee for carefully reviewing our paper and providing constructive comments, which truly improved the quality of the paper. Support for Program HST-GO-12060 and HST-GO-13309 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. PGP-G acknowledges support from Spanish Government MINECO AYA2015-70815-ERC and AYA2015-63650-P Grants., Studying giant star-forming clumps in distant galaxies is important to understand galaxy formation and evolution. At present, however, observers and theorists have not reached a consensus on whether the observed "clumps" in distant galaxies are the same phenomenon that is seen in simulations. In this paper, as a step to establish a benchmark of direct comparisons between observations and theories, we publish a sample of clumps constructed to represent the commonly observed "clumps" in the literature. This sample contains 3193 clumps detected from 1270 galaxies at 0.5 <= z < 3.0. The clumps are detected from rest-frame UV images, as described in our previous paper. Their physical properties (e.g., rest-frame color, stellar mass (M-*), star formation rate (SFR), age, and dust extinction) are measured by fitting the spectral energy distribution (SED) to synthetic stellar population models. We carefully test the procedures of measuring clump properties, especially the method of subtracting background fluxes from the diffuse component of galaxies. With our fiducial background subtraction, we find a radial clump U - V color variation, where clumps close to galactic centers are redder than those in outskirts. The slope of the color gradient (clump color as a function of their galactocentric distance scaled by the semimajor axis of galaxies) changes with redshift and M-* of the host galaxies: at a fixed M-*, the slope becomes steeper toward low redshift, and at a fixed redshift, it becomes slightly steeper with M-*. Based on our SED fitting, this observed color gradient can be explained by a combination of a negative age gradient, a negative E(B - V) gradient, and a positive specific SFR gradient of the clumps. We also find that the color gradients of clumps are steeper than those of intra-clump regions. Correspondingly, the radial gradients of the derived physical properties of clumps are different from those of the diffuse component or intra-clump regions., Ministerio de Economía y Competitividad (MINECO), NASA through a grant from the Space Telescope Science Institute, Association of Universities for Research in Astronomy, Inc., under NASA, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub