We use deep NIRCam and MIRI imaging from the James Webb Space Telescope (JWST) PRIMER survey to study the properties of ALMA-detected (sub)mm sources in the COSMOS field, with the aim of defining the cosmic history of dust-enshrouded star formation. The wealth of ALMA data in this field enabled us to isolate a robust sample of 128 (sub)mm sources within the 175 arcmin(2)PRIMER COSMOS survey footprint, spanning two decades in (sub)mm flux density. The JWST imaging is deep and red enough to reveal secure galaxy counterparts for all of these sources. This 100 per cent identification completeness is accompanied by a high level of redshift completeness: 52 per cent of the sources have spectroscopic redshifts, and this has enabled us to refine the photometric redshifts for the remaining galaxies. Armed with robust redshift information, we calculate the star formation rates (SFRs) and stellar masses (M-*) of all 128 ALMA-detected galaxies, and place them in the context of other galaxies in the field. We find that the vast majority of star formation is dust-enshrouded in all of the ALMA-detected galaxies, with SFR ranging from similar or equal to 1000 M-circle dot yr(-1). we also find that virtually all (126/128) have hi8gh stellar masses, M-* >10(10) M(circle dot)independent of redshift. The unusually high quality of our sample enables us to make a robust estimate of the contribution of the ALMA-detected galaxies to cosmic SFR density, rho(SFR). The existing ALMA imaging only covers < 20 per cent of the PRIMER COSMOS area, but based on our knowledge of all other massive galaxies in the field, we produce a completeness-corrected estimate of dust-enshrouded rho(SFR). This confirms that ultraviolet-visible star formation dominates rho(SFR) at z > 4, but also indicates that dust-enshrouded star formation still makes a contribution of similar or equal to 20 per cent at z similar or equal to 8, and similar or equal to 5 per cent at z similar or equal to 10.

We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at z ∼ 7–14. Our sample is composed of 60 galaxies at z spec ∼ 7–14, including recently confirmed galaxies at z spec = 12.34–14.18 with JWST, as well as new confirmations at z spec = 6.583–7.643 with −24 < M UV < −21 mag using ALMA and Keck. Our JWST/NIRSpec observations have also revealed that very bright galaxy candidates at z ∼ 10–13 identified from ground-based telescope images before JWST are passive galaxies at z ∼ 3–4, emphasizing the necessity of strict screening and spectroscopy in the selection of the brightest galaxies at z > 10. The UV luminosity functions derived from these spectroscopic results are consistent with a double power-law function, showing tensions with theoretical models at the bright end. To understand the origin of the overabundance of bright galaxies, we investigate their morphologies using JWST/NIRCam high-resolution images obtained in various surveys, including PRIMER and COSMOS-Web. We find that ∼70% of the bright galaxies at z ∼ 7 exhibit clumpy morphologies with multiple subcomponents, suggesting merger-induced starburst activity, which is consistent with SED fitting results showing bursty star formation histories. At z ≳ 10, bright galaxies are classified into two types of galaxies: extended ones with weak high-ionization emission lines, and compact ones with strong high-ionization lines including N iv] λ 1486, indicating that at least two different processes (e.g., merger-induced starburst and compact star formation/AGN) are shaping the physical properties of the brightest galaxies at z ≳ 10 and are responsible for their overabundance.

We present a sample of 341 “little red dots” (LRDs) spanning the redshift range z ∼ 2–11 using data from the CEERS, PRIMER, JADES, UNCOVER, and NGDEEP surveys. Unlike past use of color indices to identify LRDs, we employ continuum slope fitting using shifting bandpasses to sample the same rest-frame emission blueward and redward of the Balmer break. This enables the detection of LRDs over a wider redshift range and with less contamination from galaxies with strong breaks that otherwise lack a rising red continuum. The redshift distribution of our sample increases at z < 8 and then undergoes a rapid decline at z ∼ 4.5, which may tie the emergence of these sources to the inside-out growth that galaxies experience during this epoch. We find that LRDs are ∼1 dex more numerous than X-ray- and UV-selected active galactic nuclei (AGN) at z ∼ 5–7. Within our sample, we have identified the first two X-ray-detected LRDs. An X-ray spectral analysis confirms that these AGN are moderately obscured with log ( N H / cm 2 ) of 23 . 3 − 1.3 + 0.4 and 22.7 2 − 0.16 + 0.13 . Our analysis reveals that reddened AGN emission dominates their rest-optical light, while the rest-UV originates from their host galaxies. We also present NIRSpec observations from the RUBIES survey of 17 LRDs that show broad emission lines consistent with AGN activity. The confirmed AGN fraction of our sample is 71% for sources with F444W < 26.5. In addition, we find three LRDs with blueshifted Balmer absorption features in their spectra, suggesting an outflow of high-density, low-ionization gas from near the central engine of these faint, red AGN.

We present a sample of 341 "little red dots" (LRDs) spanning the redshift range z∼2-11 using data from the CEERS, PRIMER, JADES, UNCOVER and NGDEEP surveys. Unlike past use of color indices to identify LRDs, we employ continuum slope fitting using shifting bandpasses to sample the same rest-frame emission blueward and redward of the Balmer break. This enables the detection of LRDs over a wider redshift range and with less contamination from galaxies with strong breaks that otherwise lack a rising red continuum. The redshift distribution of our sample increases at z<8 and then undergoes a rapid decline at z∼4.5, which may tie the emergence of these sources to the inside-out growth that galaxies experience during this epoch. We find that LRDs are ∼1 dex more numerous than X-ray and UV selected AGN at z 5-7. Within our sample, we have identified the first two X-ray detected LRDs. An X-ray spectral analysis confirms that these AGN are moderately obscured with log (N_ H/ cm^2) of 23.3^+0.4_-1.3 and 22.72^+0.13_-0.16. Our analysis reveals that reddened AGN emission dominates their rest-optical light, while the rest-UV originates from their host galaxies. We also present NIRSpec observations from the RUBIES survey of 17 LRDs that show broad emission lines consistent with AGN activity. The confirmed AGN fraction of our sample is 71% for sources with F444W<26.5. In addition, we find three LRDs with blue-shifted Balmer absorption features in their spectra, suggesting an outflow of high-density, low-ionization gas from near the central engine of these faint, red AGN.

The extremely rapid assembly of the earliest galaxies during the first billion years of cosmic history is a major challenge for our understanding of galaxy formation physics. The advent of JWST has exacerbated this issue by confirming the existence of galaxies in significant numbers as early as the first few hundred million years. Perhaps even more surprisingly, in some galaxies, this initial highly efficient star formation rapidly shuts down, or quenches, giving rise to massive quiescent galaxies as little as 1.5 billion years after the Big Bang. However, due to their faintness and red colour, it has proven extremely challenging to learn about these extreme quiescent galaxies, or to confirm whether any exist at earlier times. Here we report the spectroscopic confirmation of a massive quiescent galaxy, GS-9209, at redshift $z=4.658$, just 1.25 billion years after the Big Bang, using JWST NIRSpec. From these data we infer a stellar mass of $M_* = 3.8\pm0.2\times10^{10}\ M_\odot$, which formed over a $\simeq200$ Myr period before this galaxy quenched its star formation activity at $z=6.5^{+0.2}_{-0.5}$, when the Universe was $\simeq800$ million years old. Based on the presence of broad H$\alpha$ in the spectrum and a high narrow-line [NII]/H$\alpha$ ratio, we infer the presence of an accreting supermassive black hole, with a mass of $M_\bullet = 5\pm1\times10^{8}\ M_\odot$. This large black hole mass relative to the stellar mass suggests that active galactic nucleus (AGN) feedback may have been responsible for quenching this galaxy. GS-9209 is also extremely compact, with an effective radius, $r_e=215\pm20$ parsecs. This galaxy is both a likely descendent of the highest-redshift submillimetre galaxies and quasars, and a likely progenitor for the dense, ancient cores of the most massive local galaxies.

We have derived luminosity functions, and set constraints on the UV luminosity and SFR density from z~17 to z~8, using the three most-studied JWST/NIRCam data sets, the SMACS0723, GLASS Parallel, and CEERS fields. We first used our own selections on two independent reductions of these datasets using the latest calibrations. 18 z~8, 12 z~10, 5 z~13, and 1 z~17 candidate galaxies are identified over these fields in our primary reductions, with a similar number of candidates in our secondary reductions. We then use these two reductions, applying a quantitative discriminator, to segregate the full set of z>~8 candidates reported over these fields from the literature, into three different samples, ``robust,'' ``solid,'' and ``possible''. Using all of these samples we then derive UV LF and luminosity density results at $z\geq8$, finding substantial differences. For example, including the full set of ``solid'' and ``possible'' z>~12 candidates from the literature, we find UV luminosity densities which are ~7x and ~20x higher than relying on the ``robust'' candidates alone. These results indicate the evolution of the UV LF and luminosity densities at z>~8 is still extremely uncertain, emphasizing the need for spectroscopy and deeper NIRCam+optical imaging to obtain reliable results. Nonetheless, even with the very conservative ``robust'' approach to selections, both from our own and those of other studies, we find the luminosity density from luminous (M(UV)<-19) galaxies to be ~2x larger than is easily achievable using constant star-formation efficiency models, similar to what other early JWST results have suggested.

The first few 100 Myr at z > 10 mark the last major uncharted epoch in the history of the universe, where only a single galaxy (GN-z11 at z ≈ 11) is currently spectroscopically confirmed. Here we present a search for luminous z > 10 galaxies with JWST/NIRCam photometry spanning ≈1–5 μ m and covering 49 arcmin 2 from the public JWST Early Release Science programs (CEERS and GLASS). Our most secure candidates are two M UV ≈ −21 systems: GLASS-z12 and GLASS-z10. These galaxies display abrupt ≳1.8 mag breaks in their spectral energy distributions (SEDs), consistent with complete absorption of flux bluewards of Ly α that is redshifted to z = 12.4 − 0.3 + 0.1 and z = 10.4 − 0.5 + 0.4 . Lower redshift interlopers such as quiescent galaxies with strong Balmer breaks would be comfortably detected at >5 σ in multiple bands where instead we find no flux. From SED modeling we infer that these galaxies have already built up ∼10 9 solar masses in stars over the ≲300–400 Myr after the Big Bang. The brightness of these sources enable morphological constraints. Tantalizingly, GLASS-z10 shows a clearly extended exponential light profile, potentially consistent with a disk galaxy of r 50 ≈ 0.7 kpc. These sources, if confirmed, join GN-z11 in defying number density forecasts for luminous galaxies based on Schechter UV luminosity functions, which require a survey area >10× larger than we have studied here to find such luminous sources at such high redshifts. They extend evidence from lower redshifts for little or no evolution in the bright end of the UV luminosity function into the cosmic dawn epoch, with implications for just how early these galaxies began forming. This, in turn, suggests that future deep JWST observations may identify relatively bright galaxies to much earlier epochs than might have been anticipated.

We present the deepest Spitzer/InfraRed Array Camera (IRAC) 3.6, 4.5, 5.8, and 8.0 μ 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 μ m and 4.5 μ m bands amounts to ∼4260 hr, ∼1220 hr of which are new very deep observations from the GREATS program itself. In the deepest area, the full-depth mosaics reach ≳200 hr over an area of ∼100 arcmin 2 , corresponding to a sensitivity of ∼29 AB magnitude at 3.6 μ m (1 σ for point sources). Archival cryogenic 5.8 μ m and 8.0 μ 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 μ m photometry 9192 Lyman-break galaxies at z ∼ 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.

We present the Super Eight galaxies—a set of very luminous, high-redshift (7.1 < z < 8.0) galaxy candidates found in the Brightest of Reionizing Galaxies (BoRG) Survey fields. The original sample includes eight galaxies that are Y-band dropout objects with H-band magnitudes of mH < 25.5. Four of these objects were originally reported in Calvi et al. Combining new Hubble Space Telescope (HST) WFC3/F814W imaging and Spitzer IRAC data with archival imaging from BoRG and other surveys, we explore the properties of these galaxies. Photometric redshift fitting places six of these galaxies in the redshift range of 7.1 < z < 8.0, resulting in three new high-redshift galaxies and confirming three of the four high-redshift galaxy candidates from Calvi et al. We calculate the half-light radii of the Super Eight galaxies using the HST F160W filter and find that the Super Eight sizes are in line with the typical evolution of size with redshift. The Super Eights have a mean mass of log (M*/M⊙) ∼10, which is typical for sources in this luminosity range. Finally, we place our sample on the UV z ∼ 8 luminosity function and find that the Super Eight number density is consistent with other surveys in this magnitude and redshift range.

We use a newly assembled sample of 3545 star-forming galaxies with secure spectroscopic, grism, and photometric redshifts at z = 1.5–2.5 to constrain the relationship between UV slope (β) and dust attenuation (LIR/LUV ≡ IRX). Our sample significantly extends the range of LUV and β probed in previous UV-selected samples, including those as faint as M1600 = −17.4 ( ) and −2.6 ≲ β ≲ 0.0. IRX is measured using stacks of deep Herschel data, and the results are compared with predictions of the IRX−β relation for different assumptions of the stellar population model and obscuration curve. We find that z = 1.5–2.5 galaxies have an IRX−β relation that is consistent with the predictions for an SMC curve if we invoke subsolar-metallicity models currently favored for high-redshift galaxies, while the commonly assumed starburst curve overpredicts the IRX at a given β by a factor of ≳3. IRX is roughly constant with LUV for LUV ≳ 3 × 109 L⊙. Thus, the commonly observed trend of fainter galaxies having bluer β may simply reflect bluer intrinsic slopes for such galaxies, rather than lower obscurations. The IRX−β relation for young/low-mass galaxies at z ≳ 2 implies a dust curve that is steeper than the SMC. The lower attenuations and higher ionizing photon output for low-metallicity stellar populations point to Lyman continuum production efficiencies, ξion, that may be elevated by a factor of ≈2 relative to the canonical value for L* galaxies, aiding in their ability to keep the universe ionized at z ∼ 2.

We report on the discovery of three especially bright candidate galaxies. Five sources were targeted for follow-up with the Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3), selected from a larger sample of 16 bright ( mag) candidate Lyman break galaxies (LBGs) identified over 1.6 degrees2 of the COSMOS/UltraVISTA field. These were selected as Y and J dropouts by leveraging the deep (Y-to- mag, ) NIR data from the UltraVISTA DR3 release, deep ground-based optical imaging from the CFHTLS and Suprime-Cam programs, and Spitzer/IRAC mosaics combining observations from the SMUVS and SPLASH programs. Through the refined spectral energy distributions, which now also include new HyperSuprimeCam g-, r-, i-, z-, and Y-band data, we confirm that 3/5 galaxies have robust , consistent with the initial selection. The remaining 2/5 galaxies have a nominal . However, with HST data alone, these objects have increased probability of being at . We measure mean UV continuum slopes for the three galaxies, marginally bluer than similarly luminous in CANDELS but consistent with previous measurements of similarly luminous galaxies at . The circularized effective radius for our brightest source is 0.9 ± 0.3 kpc, similar to previous measurements for a bright galaxy and bright galaxies. Finally, enlarging our sample to include the six brightest LBGs identified over UltraVISTA (i.e., including three other sources from Labbé et al.) we estimate for the first time the volume density of galaxies at the extreme bright end ( mag) of the UV luminosity function. Despite this exceptional result, the still large statistical uncertainties do not allow us to discriminate between a Schechter and a double-power-law form.

We measure the evolution of the specific star formation rate (sSFR = SFR/Mstellar) between redshift 4 and 6 to assess the reported “constant” sSFR at z > 2. We derive stellar masses and star formation rates (SFRs) for a large sample of 750 z ∼ 4–6 galaxies in the GOODS-S field by fitting stellar population models to their spectral energy distributions. Dust extinction is derived from the observed UV colors. We evaluate different star formation histories (SFHs, constant and rising with time) and the impact of optical emission lines. The SFR and Mstellar values are insensitive to whether the SFH is constant or rising. The derived sSFR is very similar (within 0.1 dex) in two Mstellar bins centered at 1 and 5 × 109 M☉. The effect of emission lines was, however, quite pronounced. Assuming no contribution from emission lines, the sSFR for galaxies at 5 × 109 M☉ evolves weakly at z > 2 (sSFR(z)∝(1 + z)0.6 ± 0.1), consistent with previous results. When emission lines are included in the rest-frame optical bands, consistent with the observed Infrared Array Camera [3.6] and [4.5] fluxes, the sSFR shows higher values at high redshift following sSFR(z)∝(1 + z)1.0 ± 0.1, i.e., the best-fit evolution shows a sSFR ∼2.3 × higher at z ∼ 6 than at z ∼ 2. This is, however, a substantially weaker trend than that found at z < 2 and even than that expected from current models for z > 2 (sSFR(z)∝(1 + z)2.5). Even accounting for emission lines, the observed sSFR(z) trends at z > 2 are still in tension with theoretical expectations.

We use the ultra-deep HUDF09 and the deep ERS data from the HST WFC3/IR camera, along with the wide area Spitzer/IRAC data from GOODS-S to derive SEDs of star-forming galaxies from the rest-frame UV to the optical over a wide luminosity range (M_1500 -21 to M_1500 -18) from z 7 to z 4. The sample contains 400 z 4, 120 z 5, 60 z 6, and 36 prior z 7 galaxies. Median stacking enables the first comprehensive study of very faint high-z galaxies at multiple redshifts (e.g., [3.6] = 27.4 +/- 0.1 AB mag for the M_1500 -18 sources at z 4). At z 4 our faint median-stacked SEDs reach to 0.06 L*(z=4) and are combined with recently published results at high luminosity L > L* that extend to M_1500 -23. We use the observed SEDs and template fits to derive rest frame UV-to-optical colors (U - V) at all redshifts and luminosities. We find that this color does not vary significantly with redshift at a fixed luminosity. The UV-to-optical color does show a weak trend with luminosity, becoming redder at higher luminosities. This is most likely due to dust. At z > 5 we find blue colors [3.6]-[4.5] -0.3 mag that are most likely due to rest-frame optical emission lines contributing to the flux in the IRAC filter bandpasses. The scatter across our derived SEDs remains substantial, but the results are most consistent with a lack of any evolution in the SEDs with redshift at a given luminosity. The similarity of the SEDs suggests a self-similar mode of evolution over a timespan from 0.7 Gyr to 1.5 Gyr that encompasses very substantial growth in the stellar mass density in the universe (from 4x10^6 to 2x10^7 Msun Mpc^-3).

We present 3D-HST, a near-infrared spectroscopic Treasury program with the Hubble Space Telescope for studying the physical processes that shape galaxies in the distant universe. 3D-HST provides rest-frame optical spectra for a sample of ∼7000 galaxies at 1 < z < 3.5, the epoch when ∼60% of all star formation took place, the number density of quasars peaked, the first galaxies stopped forming stars, and the structural regularity that we see in galaxies today must have emerged. 3D-HST will cover three quarters (625 arcmin2) of the CANDELS Treasury survey area with two orbits of primary WFC3/G141 grism coverage and two to four orbits with the ACS/G800L grism in parallel. In the IR, these exposure times yield a continuum signal-to-noise ratio of ∼5 per resolution element at H140 ∼ 23.1 and a 5σ emission-line sensitivity of ∼5 × 10−17 erg s−1 cm−2 for typical objects, improving by a factor of ∼2 for compact sources in images with low sky background levels. The WFC3/G141 spectra provide continuous wavelength coverage from 1.1 to 1.6 μm at a spatial resolution of ∼0. ′′13, which, combined with their depth, makes them a unique resource for studying galaxy evolution. We present an overview of the preliminary reduction and analysis of the grism observations, including emission-line and redshift measurements from combined fits to the extracted grism spectra and photometry from ancillary multi-wavelength catalogs. The present analysis yields redshift estimates with a precision of σ (z) = 0.0034(1 + z), or σ (v) ≈ 1000 km s−1. We illustrate how the generalized nature of the survey yields near-infrared spectra of remarkable quality for many different types of objects, including a quasar at z = 4.7, quiescent galaxies at z ∼ 2, and the most distant T-type brown dwarf star known. The combination of the CANDELS and 3D-HST surveys will provide the definitive imaging and spectroscopic data set for studies of the 1 < z < 3.5 universe until the launch of the James Webb Space Telescope.

We present first results from the 3D-HST program, a near-IR spectroscopic survey performed with the Wide Field Camera 3 on the Hubble Space Telescope. We have used 3D-HST spectra to measure redshifts and Halpha equivalent widths for a stellar mass-limited sample of 34 galaxies at 110^11 M(sun) in the COSMOS, GOODS, and AEGIS fields. We find that a substantial fraction of massive galaxies at this epoch are forming stars at a high rate: the fraction of galaxies with Halpha equivalent widths >10 A is 59%, compared to 10% among SDSS galaxies of similar masses at z=0.1. Galaxies with weak Halpha emission show absorption lines typical of 2-4 Gyr old stellar populations. The structural parameters of the galaxies, derived from the associated WFC3 F140W imaging data, correlate with the presence of Halpha: quiescent galaxies are compact with high Sersic index and high inferred velocity dispersion, whereas star-forming galaxies are typically large two-armed spiral galaxies, with low Sersic index. Some of these star forming galaxies might be progenitors of the most massive S0 and Sa galaxies. Our results challenge the idea that galaxies at fixed mass form a homogeneous population with small scatter in their properties. Instead we find that massive galaxies form a highly diverse population at z>1, in marked contrast to the local Universe.

We use ∼88 arcmin2 of deep (≳26.5 mag at 5σ) NICMOS data over the two GOODS fields and the HDF-South to conduct a search for bright z ≳ 7 galaxy candidates. This search takes advantage of an efficient preselection over 58 arcmin2 of NICMOS H160-band data where only plausible z ≳ 7 candidates are followed up with NICMOS J110-band observations. ∼248 arcmin2 of deep ground-based near-infrared data (≳25.5 mag, 5σ) are also considered in the search. In total, we report 15 z850-dropout candidates over this area—7 of which are new to these search fields. Two possible z ∼ 9 J110-dropout candidates are also found, but seem unlikely to correspond to z ∼ 9 galaxies (given the estimated contamination levels). The present z ∼ 9 search is used to set upper limits on the prevalence of such sources. Rigorous testing is undertaken to establish the level of contamination of our selections by photometric scatter, low-mass stars, supernovae, and spurious sources. The estimated contamination rate of our z ∼ 7 selection is ∼24%. Through careful simulations, the effective volume available to our z ≳ 7 selections is estimated and used to establish constraints on the volume density of luminous (L*z = 3, or ∼−21 mag) galaxies from these searches. We find that the volume density of luminous star-forming galaxies at z ∼ 7 is 13+8−5 times lower than at z ∼ 4 and >25 times lower (1σ) at z ∼ 9 than at z ∼ 4. This is the most stringent constraint yet available on the volume density of ≳L*z = 3 galaxies at z ∼ 9. The present wide-area, multi-field search limits cosmic variance to ≲20%. The evolution we find at the bright end of the UV LF is similar to that found from recent Subaru Suprime-Cam, HAWK-I or ERS WFC3/IR searches. The present paper also includes a complete summary of our final z ∼ 7 z850-dropout sample (18 candidates) identified from all NICMOS observations to date (over the two GOODS fields, the HUDF, galaxy clusters).