In November 2022, the James Webb Space Telescope (JWST) returned deep near-infrared images of Abell 2744 -- a powerful lensing cluster capable of magnifying distant, incipient galaxies beyond it. ...Together with the existing Hubble Space Telescope (HST) imaging, this publicly available dataset opens a fundamentally new discovery space to understand the remaining mysteries of the formation and evolution of galaxies across cosmic time. In this work, we detect and measure some 60,000 objects across the 49 arcmin\(^2\) JWST footprint down to a \(5\,\sigma\) limiting magnitude of \(\sim\)30 mag in 0.32" apertures. Photometry is performed using circular apertures on images matched to the point spread function of the reddest NIRCam broad band, F444W, and cleaned of bright cluster galaxies and the related intra-cluster light. To give an impression of the photometric performance, we measure photometric redshifts and achieve a \(\sigma_{\rm NMAD}\approx0.03\) based on known, but relatively small, spectroscopic samples. With this paper, we publicly release our HST and JWST PSF-matched photometric catalog with optimally assigned aperture sizes for easy use, along with single aperture catalogs, photometric redshifts, rest-frame colors, and individual magnification estimates. These catalogs will set the stage for efficient and deep spectroscopic follow-up of some of the first JWST-selected samples in Summer 2023.
JWST is revealing a new population of dust-reddened broad-line active
galactic nuclei (AGN) at redshifts $z\gtrsim5$. Here we present deep
NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program ...UNCOVER of 15 AGN
candidates selected to be compact, with red continua in the rest-frame optical
but with blue slopes in the UV. From NIRCam photometry alone, they could have
been dominated by dusty star formation or AGN. Here we show that the majority
of the compact red sources in UNCOVER are dust-reddened AGN: $60\%$ show
definitive evidence for broad-line H$\alpha$ with FWHM$\, >2000$ km/s, for
$20\%$ current data are inconclusive, and $20\%$ are brown dwarf stars. We
propose an updated photometric criterion to select red $z>5$ AGN that excludes
brown dwarfs and is expected to yield $>80\%$ AGN. Remarkably, among all
$z_{\rm phot}>5$ galaxies with F277W$-$F444W$>1$ in UNCOVER at least $33\%$ are
AGN regardless of compactness, climbing to at least $80\%$ AGN for sources with
F277W$-$F444W$>1.6$. The confirmed AGN have black hole masses of $10^7-10^9$
M$_{\odot}$. While their UV-luminosities ($-16>M_{\rm UV}>-20$ AB mag) are low
compared to UV-selected AGN at these epochs, consistent with percent-level
scattered AGN light or low levels of unobscured star formation, the inferred
bolometric luminosities are typical of $10^7-10^9$ M$_{\odot}$ black holes
radiating at $\sim 10-40\%$ of Eddington. The number densities are surprisingly
high at $\sim10^{-5}$ Mpc$^{-3}$ mag$^{-1}$, 100 times more common than the
faintest UV-selected quasars, while accounting for $\sim1\%$ of the UV-selected
galaxies. While their UV-faintness suggest they may not contribute strongly to
reionization, their ubiquity poses challenges to models of black hole growth.
We report the discovery of 15 exceptionally luminous $10\lesssim z\lesssim14$
candidate galaxies discovered in the first 0.28 deg$^2$ of JWST/NIRCam imaging
from the COSMOS-Web Survey. These sources ...span rest-frame UV magnitudes of
$-20.5>M_{\rm UV}>-22$, and thus constitute the most intrinsically luminous
$z\gtrsim10$ candidates identified by JWST to-date. Selected via NIRCam imaging
with Hubble ACS/F814W, deep ground-based observations corroborate their
detection and help significantly constrain their photometric redshifts. We
analyze their spectral energy distributions using multiple open-source codes
and evaluate the probability of low-redshift solutions; we conclude that 12/15
(80%) are likely genuine $z\gtrsim10$ sources and 3/15 (20%) likely
low-redshift contaminants. Three of our $z\sim12$ candidates push the limits of
early stellar mass assembly: they have estimated stellar masses
$\sim5\times10^{9}\,M_\odot$, implying an effective stellar baryon fraction of
$\epsilon_{\star}\sim0.2-0.5$, where $\epsilon_{\star}\equiv
M_{\star}/(f_{b}M_{halo})$. The assembly of such stellar reservoirs is made
possible due to rapid, burst-driven star formation on timescales $<$100\,Myr
where the star-formation rate may far outpace the growth of the underlying dark
matter halos. This is supported by the similar volume densities inferred for
$M_\star\sim10^{10}\,M_\odot$ galaxies relative to $M_\star\sim10^{9}\,M_\odot$
-- both about $10^{-6}$ Mpc$^{-3}$ -- implying they live in halos of comparable
mass. At such high redshifts, the duty cycle for starbursts would be of order
unity, which could cause the observed change in the shape of the UVLF from a
double powerlaw to Schechter at $z\approx8$. Spectroscopic redshift
confirmation and ensuing constraints of their masses will be critical to
understanding how, and if, such early massive galaxies push the limits of
galaxy formation in $\Lambda$CDM.
This paper presents a new search for $z\geq7.5$ galaxies using the COSMOS2020
photometric catalogues. Finding galaxies at the reionization epoch through deep
imaging surveys remains observationally ...challenging. The larger area covered by
ground-based surveys like COSMOS enables the discovery of the brightest
galaxies at these high redshifts. Covering $1.4$deg$^2$, our COSMOS catalogues
were constructed from the latest UltraVISTA data release (DR4) combined with
the final Spitzer/IRAC COSMOS images and the Hyper-Suprime-Cam Subaru Strategic
Program DR2 release. We identify $17$ new $7.5<z<10$ candidate sources, and
confirm $15$ previously published candidates. Using deblended photometry
extracted by fitting surface brightness models on multi-band images, we select
four candidates which would be rejected using fixed aperture photometry. We
test the robustness of all our candidates by comparing six different
photometric redshift estimates. Finally, we compute the galaxy UV luminosity
function in three redshift bins centred at $z=8,9,10$. We find no clear
evolution of the number density of the brightest galaxies $M_\text{UV}<-21.5$,
in agreement with previous works. Rapid changes in the quenching efficiency or
attenuation by dust could explain such lack of evolution between $z\sim 8$ and
$z\sim 9. A spectroscopic confirmation of the redshifts, already planned with
JWST and the Keck telescopes, will be essential to confirm our results.
A growing number of far-infrared bright sources completely invisible in deep extragalactic optical surveys hint at an elusive population of z>4 dusty, star-forming galaxies. Cycle 1 JWST surveys are ...now detecting their rest-frame optical light, which provides key insight into their stellar properties and statistical constraints on the population as a whole. This work presents the JWST/NIRCam counterpart from the COSMOS-Web survey to a far-infrared SCUBA-2 and ALMA source, AzTECC71, which was previously undetected at wavelengths shorter than 850 microns. AzTECC71, amongst the reddest galaxies in COSMOS-Web with F277W - F444W~0.9, is undetected in NIRCam/F150W and F115W and fainter in F444W than other sub-millimeter galaxies identified in COSMOS-Web by 2-4 magnitudes. This is consistent with the system having both a lower stellar mass and higher redshift than the median dusty, star-forming galaxy. With deep ground- and space-based upper limits combined with detections in F277W, F444W and the far-IR including ALMA Band 6, we find a high probability (99%) that AzTECC71 is at z>4 with z_phot=5.7(+0.8,-0.7). This galaxy is massive (logM*/Msun~10.7) and IR-luminous (logLIR/Lsun~12.7), comparable to other optically-undetected but far-IR bright dusty, star-forming galaxies at z>4. This population of luminous, infrared galaxies at z>4 is largely unconstrained but comprises an important bridge between the most extreme dust-obscured galaxies and more typical high-redshift star-forming galaxies. If further far-IR-selected galaxies that drop out of the F150W filter in COSMOS-Web have redshifts z>4 like AzTECC71, then the volume density of such sources may be ~3-10x greater than previously estimated.
In this paper we describe the survey design for the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) Cycle 1 JWST Treasury program, which executed its early ...imaging component in November 2022. The UNCOVER survey includes ultradeep (\(\sim29-30\mathrm{AB}\)) imaging of \(\sim\)45 arcmin\(^2\) on and around the well-studied Abell 2744 galaxy cluster at \(z=0.308\) and will follow-up \({\sim}500\) galaxies with extremely deep low-resolution spectroscopy with the NIRSpec/PRISM during the summer of 2023. We describe the science goals, survey design, target selection, and planned data releases. We also present and characterize the depths of the first NIRCam imaging mosaic, highlighting previously unparalleled resolved and ultradeep 2-4 micron imaging of known objects in the field. The UNCOVER primary NIRCam mosaic spans 28.8 arcmin\(^2\) in seven filters (F115W, F150W, F200W, F277W, F356W, F410M, F444W) and 16.8 arcmin\(^2\) in our NIRISS parallel (F115W, F150W, F200W, F356W, and F444W). To maximize early community use of the Treasury data set, we publicly release full reduced mosaics of public JWST imaging including 45 arcmin\(^2\) NIRCam and 17 arcmin\(^2\) NIRISS mosaics on and around the Abell 2744 cluster, including the Hubble Frontier Field primary and parallel footprints.
A&A 677, A184 (2023) How galaxies form, assemble, and cease their star-formation is a central
question within the modern landscape of galaxy evolution studies. These
processes are indelibly imprinted ...on the galaxy stellar mass function (SMF). We
present constraints on the shape and evolution of the SMF, the quiescent galaxy
fraction, and the cosmic stellar mass density across 90% of the history of the
Universe from $z=7.5\rightarrow0.2$ via the COSMOS survey. Now with deeper and
more homogeneous near-infrared coverage exploited by the COSMOS2020 catalog, we
leverage the large 1.27 deg$^{2}$ effective area to improve sample statistics
and understand cosmic variance particularly for rare, massive galaxies and push
to higher redshifts with greater confidence and mass completeness than previous
studies. We divide the total stellar mass function into star-forming and
quiescent sub-samples through $NUVrJ$ color-color selection. Measurements are
then fitted with Schechter functions to infer the intrinsic SMF, the evolution
of its key parameters, and the cosmic stellar mass density out to $z=7.5$. We
find a smooth, monotonic evolution in the galaxy SMF since $z=7.5$, in
agreement with previous studies. The number density of star-forming systems
seems to have undergone remarkably consistent growth spanning four decades in
stellar mass from $z=7.5\rightarrow2$ whereupon high-mass systems become
predominantly quiescent (i.e. downsizing). An excess of massive systems at
$z\sim2.5-5.5$ with strikingly red colors, some newly identified, increase the
observed number densities to the point where the SMF cannot be reconciled with
a Schechter function. Systematics including cosmic variance and/or AGN
contamination are unlikely to fully explain this excess, and so we speculate
that there may be contributions from dust-obscured objects similar to those
found in FIR surveys. (abridged)
We present the characteristics of 2mm-selected sources from the largest Atacama Large Millimeter and submillimeter Array (ALMA) blank-field contiguous survey conducted to-date, the Mapping ...Obscuration to Reionization with ALMA (MORA) survey covering 184arcmin\(^2\) at 2mm. Twelve of the thirteen detections above 5\(\sigma\) are attributed to emission from galaxies, eleven of which are dominated by cold dust emission. These sources have a median redshift of \(\langle z_{\rm 2mm}\rangle=3.6^{+0.4}_{-0.3}\) primarily based on optical/near-infrared (OIR) photometric redshifts with some spectroscopic redshifts, with 77\(\pm\)11% of sources at \(z>3\) and 38\(\pm\)12% of sources at \(z>4\). This implies that 2mm selection is an efficient method for identifying the highest redshift dusty star-forming galaxies (DSFGs). Lower redshift DSFGs (\(z<3\)) are far more numerous than those at \(z>3\) yet likely to drop out at 2mm. MORA shows that DSFGs with star-formation rates in excess of 300M\(_\odot\) yr\(^{-1}\) and relative rarity of \(\sim\)10\(^{-5}\) Mpc\(^{-3}\) contribute \(\sim\)30% to the integrated star-formation rate density between \(3<z<6\). The volume density of 2mm-selected DSFGs is consistent with predictions from some cosmological simulations and is similar to the volume density of their hypothesized descendants: massive, quiescent galaxies at \(z>2\). Analysis of MORA sources' spectral energy distributions hint at steeper empirically-measured dust emissivity indices than typical literature studies, with \(\langle\beta\rangle=2.2^{+0.5}_{-0.4}\). The MORA survey represents an important step in taking census of obscured star-formation in the Universe's first few billion years, but larger area 2mm surveys are needed to more fully characterize this rare population and push to the detection of the Universe's first dusty galaxies.
The Cosmic Evolution Survey (COSMOS) has become a cornerstone of
extragalactic astronomy. Since the last public catalog in 2015, a wealth of new
imaging and spectroscopic data has been collected in ...the COSMOS field. This
paper describes the collection, processing, and analysis of this new imaging
data to produce a new reference photometric redshift catalog. Source detection
and multi-wavelength photometry is performed for 1.7 million sources across the
$2\,\mathrm{deg}^{2}$ of the COSMOS field, $\sim$966,000 of which are measured
with all available broad-band data using both traditional aperture photometric
methods and a new profile-fitting photometric extraction tool, The Farmer,
which we have developed. A detailed comparison of the two resulting photometric
catalogs is presented. Photometric redshifts are computed for all sources in
each catalog utilizing two independent photometric redshift codes. Finally, a
comparison is made between the performance of the photometric methodologies and
of the redshift codes to demonstrate an exceptional degree of self-consistency
in the resulting photometric redshifts. The $i<21$ sources have sub-percent
photometric redshift accuracy and even the faintest sources at $25<i<27$ reach
a precision of $5\,\%$. Finally, these results are discussed in the context of
previous, current, and future surveys in the COSMOS field. Compared to
COSMOS2015, reaches the same photometric redshift precision at almost one
magnitude deeper. Both photometric catalogs and their photometric redshift
solutions and physical parameters will be made available through the usual
astronomical archive systems (ESO Phase 3, IPAC IRSA, and CDS).
Stimulation of the TCR of activated, mature T cells by an APC produces a spectrum of functional responses. Most of those responses positively promote immunity and inflammation. However, death of the ...responding T cell, which would limit subsequent inflammation, can also result from such stimulation. We compare the Ag threshold necessary to promote inflammation through cytokine production with the Ag threshold necessary to limit inflammation through T cell death. These two responses are independently regulated by the APC and this regulation is selective for both different APC products and different T cell subsets. The costimulator B7 selectively decreases the Ag threshold for cytokine production in Th1 cells with no effect on the Ag threshold for Th1 death. B7 has no effect on the Th2 Ag threshold for cytokine production or death. In contrast, IFN-gamma negatively modulates a macrophage product that selectively increases the threshold of Ag necessary to stimulate death in Th2 cells, but has no effect on cytokine production by Th2 cells or cytokine production or death of Th1 cells. This selective regulation of cytokine production and T cell death may play an important role in both shaping the quality of a given immune response and in providing a general mechanism for the regulation of the immune response by limiting inflammation and through peripheral deletion of inappropriate T cell specificities.
