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We present the properties of a massive, large, dusty, metal-rich, star-forming galaxy at z_spec=6.73. GOODSN-100182 was observed with JWST/NIRSpec as part of the AURORA survey, and is also covered by public multi-wavelength HST and JWST imaging. While the large mass of GOODSN-100182 (~10^10 M_sun) was indicated prior to JWST, NIRCam rest-optical imaging now reveals the presence of an extended disk (r_eff~1.5 kpc). In addition, the NIRSpec R~1000 spectrum of GOODSN-100182 includes the detection of a large suite of rest-optical nebular emission lines ranging in wavelength from [OII]3727 up to [NII]6583. The ratios of Balmer lines suggest significant dust attenuation (E(B-V)_gas=0.40+0.10/-0.09), consistent with the red rest-UV slope inferred for GOODSN-100182 (beta=-0.50+/-0.09). The star-formation rate based on dust-corrected H-alpha emission is log(SFR(H-alpha)/ M_sun/yr)=2.02+0.13/-0.14, well above the z~7 star-forming main sequence in terms of specific SFR. Strikingly, the ratio of [NII]6583/H-alpha emission suggests almost solar metallicity, as does the ratio ([OIII]5007/H-beta)/([NII]6583/H-alpha) and the detection of the faint [FeII]4360 emission feature, whereas the [OIII]5007/[OII]3727 ratio suggests roughly 50% solar metallicity. Overall, the excitation and ionization properties of GOODSN-100182 more closely resemble those of typical star-forming galaxies at z~2-3 rather than z~7. Based on public spectroscopy of the GOODS-N field, we find that GOODSN-100182 resides within a significant galaxy overdensity, and is accompanied by a spectroscopically-confirmed neighbor galaxy. GOODSN-100182 demonstrates the existence of mature, chemically-enriched galaxies within the first billion years of cosmic time, whose properties must be explained by galaxy formation models., Comment: 16 pages, 13 figures, submitted to ApJ

We examine star-formation and dust properties for a sample of 660 galaxies at $1.37\leq z\leq 2.61$ in the MOSDEF survey by dividing them into groups with similarly-shaped spectral energy distributions (SEDs). For each group, we combine the galaxy photometry into a finely-sampled composite SED, and stack their spectra. This method enables the study of more complete galaxy samples, including galaxies with very faint emission lines. We fit these composite SEDs with Prospector to measure the stellar attenuation and SED-based star-formation rates (SFRs). We also derive emission-line properties from the spectral stacks, including Balmer decrements, dust-corrected SFRs, and metallicities. We find that stellar attenuation correlates most strongly with mass, while nebular attenuation correlates strongly with both mass and SFR. Furthermore, the excess of nebular compared to stellar attenuation correlates most strongly with SFR. The highest SFR group has 2 mag of excess nebular attenuation. Our results are consistent with a model in which star-forming regions become more dusty as galaxy mass increases. To explain the increasing excess nebular attenuation, we require a progressively larger fraction of star formation to occur in highly-obscured regions with increasing SFR. This highly-obscured star formation could occur in dusty clumps or central starbursts. Additionally, as each galaxy group represents a different evolutionary stage, we study their locations on the UVJ and SFR-mass diagrams. As mass increases, metallicity and dust attenuation increase, while sSFR decreases. However, the most massive group moves towards the quiescent region of the UVJ diagram, while showing less obscuration, potentially indicating removal of dust., Comment: 21 pages, 7 figures, accepted for publication in ApJ

We use JWST/NIRSpec observations from the Assembly of Ultradeep Rest-optical Observations Revealing Astrophysics (AURORA) survey to constrain the shape of the nebular attenuation curve of a star-forming galaxy at z=4.41, GOODSN-17940. We utilize 11 unblended HI recombination lines to derive the attenuation curve spanning optical to near-infrared wavelengths (3751-9550 \r{A}). We then leverage a high-S/N spectroscopic detection of the rest-frame ultraviolet continuum in combination with rest-UV photometric measurements to constrain the shape of the curve at ultraviolet wavelengths. While this UV constraint is predominantly based on stellar emission, the large measured equivalent widths of H$\alpha$ and H$\beta$ indicate that GOODSN-17940 is dominated by an extremely young stellar population <10 Myr in age such that the UV stellar continuum experiences the same attenuation as the nebular emission. The resulting combined nebular attenuation curve spans 1400-9550 \r{A} and has a shape that deviates significantly from commonly assumed dust curves in high-redshift studies. Relative to the Milky Way, SMC, and Calzetti curves, the new curve has a steeper slope at long wavelengths ($\lambda>5000$ \r{A}) while displaying a similar slope across blue-optical wavelengths ($\lambda=3750-5000$ \r{A}). In the ultraviolet, the new curve is shallower than the SMC and Calzetti curves and displays no significant 2175 \r{A} bump. This work demonstrates that the most commonly assumed dust curves are not appropriate for all high-redshift galaxies. These results highlight the ability to derive nebular attenuation curves for individual high-redshift sources with deep JWST/NIRSpec spectroscopy, thereby improving the accuracy of physical properties inferred from nebular emission lines., Comment: 21 pages, 6 figures, 1 table, submitted to ApJ

We present the design and observations of low resolution JWST/NIRSpec PRISM spectroscopy from the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) Cycle 1 JWST Treasury program. Targets are selected using JWST/NIRCam photometry from UNCOVER and other programs, and cover a wide range of categories and redshifts to ensure the legacy value of the survey. These categories include the first galaxies at $z\gtrsim10$, faint galaxies during the Epoch of Reionization ($z\sim6-8$), high redshift AGN ($z\gtrsim6$), Population III star candidates, distant quiescent and dusty galaxies ($1\lesssim z \lesssim 6$), and filler galaxies sampling redshift--color--magnitude space from $z\sim 0.1-13$. Seven NIRSpec MSA masks across the extended Abell 2744 cluster were observed, along with NIRCam parallel imaging in 8 filters (F090W, F115W, F150W, F200W, F277W, F356W, F410M, F444W, F480M) over a total area of ~26 arcmin$^2$, overlapping existing HST coverage from programs including the Hubble Frontier Fields and BUFFALO. We successfully observed 553 objects down to $m_{\mathrm{F444W}}\sim30\mathrm{AB}$, and by leveraging mask overlaps, we reach total on-target exposure times ranging from 2.4-16.7h. We demonstrate the success rate and distribution of confirmed redshifts, and also highlight the rich information revealed by these ultradeep spectra for a subset of our targets. An updated lens model of Abell 2744 is also presented, including 14 additional spectroscopic redshifts and finding a total cluster mass of $M_{\mathrm{SL}}=(2.1\pm0.3)\times10^{15}\,\mathrm{M}_{\odot}$. We publicly release reduced 1D and 2D spectra for all objects observed in Summer 2023 along with a spectroscopic redshift catalog and the updated lens model of the cluster (https://jwst-uncover.github.io/DR4.html)., Comment: 19 pages, 9 figures, 4 tables, submitted to ApJ, comments welcome! Data available at: https://jwst-uncover.github.io/DR4.html (v2: figure format correction)

Post-starburst galaxies (PSBs) are young quiescent galaxies that have recently experienced a rapid decrease in star formation, allowing us to probe the fast-quenching period of galaxy evolution. In this work, we obtained HST WFC3/F110W imaging to measure the sizes of 171 massive ($\mathrm{log(M_{*}/M_{\odot})\sim\,11)}$ spectroscopically identified PSBs at $1

We present spatially resolved, simple stellar population equivalent ages, stellar metallicities, and abundance ratios for 456 massive ($10.3\lesssim\log(\mathrm{M}_*/\mathrm{M}_\odot)\lesssim11.8$) quiescent galaxies at $0.6\lesssim z\lesssim1.0$ from the Large Early Galaxy Astrophysics Census, derived using full-spectrum models. Typically, we find flat age and [Mg/Fe] gradients, and negative [Fe/H] gradients, implying iron-rich cores. We also estimate intrinsic [Fe/H] gradients via forward modelling. We examine the observed gradients in three age bins. Younger quiescent galaxies typically have negative [Fe/H] gradients and positive age gradients, possibly indicating a recent central starburst. Additionally, this finding suggests that photometrically measured flat colour gradients in young quiescent galaxies are the result of the positive age and negative metallicity gradients cancelling each other. For older quiescent galaxies, the age gradients become flat and [Fe/H] gradients weaken, though remain negative. Thus, negative colour gradients at older ages are likely driven by metallicity gradients. The diminishing age gradient may result from the starburst fading. Furthermore, the persistence of the [Fe/H] gradients may suggest that the outskirts are simultaneously built up by mergers with lower metallicity satellites. On the other hand, the gradients could be inherited from the star-forming phase, in which case mergers may not be needed to explain our findings. This work illustrates the need for resolved spectroscopy, instead of just photometry, to measure stellar population gradients. Extending these measurements to higher redshift is imperative for understanding how stellar populations in quiescent galaxies are assembled over cosmic time., Comment: Accepted for publication in MNRAS; minor typesetting corrections after copyediting

Spectroscopic studies of elliptical galaxies show that their stellar population ages, mean metallicity, and $\alpha$-enhancement traced by [Mg/Fe] all increase with galaxy stellar mass or velocity dispersion. We use one-zone galactic chemical evolution (GCE) models with a flexible star formation history (SFH) to model the age, [Mg/H], and [Mg/Fe] inferred from simple stellar population (SSP) fits to observed ellipticals at $z \sim 0$ and $z \sim 0.7$. We show that an SSP fit to the spectrum computed from a full GCE model gives ages and abundances close to the light-weighted, logarithmically averaged values of the composite stellar population, , <[Mg/H]>, and <[Mg/Fe]>. With supernova Mg and Fe yields fixed to values motivated by Milky Way stellar populations, we find that predicted <[Mg/H]>- and <[Mg/Fe]>- relations are surprisingly insensitive to SFH parameters: older galaxies have higher <[Mg/Fe]>, but the detailed form of the SFH has limited impact. The star formation efficiency and outflow efficiency affect the early and late evolution of <[Mg/H]>, respectively; explaining observed trends requires higher star formation efficiency and lower outflows in more massive galaxies. With core collapse supernova yields calibrated to the plateau [Mg/Fe]$_{\rm cc} \approx0.45$ observed in many Milky Way studies, our models underpredict the observed <[Mg/Fe]> ratios of ellipticals by 0.05-0.1 dex. Increasing the core collapse yield ratio to [Mg/Fe]$_{\rm cc} = 0.55$ improves the agreement, though the models still lie below the data. We discuss potential resolutions of this discrepancy, including the possibility that many ellipticals terminate their star formation with a self-enriching, terminating burst that reduces the light-weighted age and boosts <[Mg/Fe]>.

We present the stellar metallicities and multi-element abundances (C, Mg, Si, Ca, Ti, Cr, and Fe) of 15 massive (log $M/M_\odot=10.2-11.2$) quiescent galaxies at z=1-3, derived from ultradeep JWST-SUSPENSE spectra. Compared to quiescent galaxies at z~0, these galaxies exhibit a deficiency of 0.26$\pm0.04$ dex in [C/H], 0.16$\pm0.03$ dex in [Fe/H], and 0.07$\pm0.04$ dex in [Mg/H], implying rapid formation and quenching before significant enrichment from asymptotic giant branch stars and Type Ia supernovae. Additionally, we find that galaxies forming at higher redshift consistently show higher [Mg/Fe] and lower [Fe/H] and [Mg/H], regardless of their observed redshift. The evolution in [Fe/H] and [C/H] is therefore primarily driven by lower-redshift samples naturally including galaxies with longer star-formation timescales. In contrast, the lower [Mg/H] likely reflects earlier-forming galaxies expelling larger gas reservoirs during their quenching phase. Consequently, the mass-metallicity relation, primarily reflecting [Mg/H], is somewhat lower at z=1-3 compared to the lower redshift relation. Finally, we compare our results to standard stellar population modeling approaches employing solar abundance patterns and non-parametric star-formation histories (using Prospector). Our SSP-equivalent ages agree with the mass-weighted ages from Prospector, while the metallicities disagree significantly. Nonetheless, the metallicities better reflect [Fe/H] than total [Z/H]. We also find that star-formation timescales inferred from elemental abundances are significantly shorter than those from Prospector, and we discuss the resulting implications for the early formation of massive galaxies., Comment: Accepted to ApJ; 22 pages, 6 figures, 3 tables

We present results on the emission-line properties of z=1.4-7.5 star-forming galaxies in the Assembly of Ultradeep Rest-optical Observations Revealing Astrophysics (AURORA) Cycle 1 JWST/NIRSpec program. Based on its depth, continuous wavelength coverage from 1--5 microns, and medium spectral resolution (R~1000), AURORA includes detections of a large suite of nebular emission lines spanning a broad range in rest wavelength. We investigate the locations of AURORA galaxies in multiple different emission-line diagrams, including traditional "BPT" diagrams of [OIII]/Hbeta vs. [NII]/Halpha, [SII]/Halpha, and [OI]/Halpha, and the "ionization-metallicity" diagram of [OIII]/[OII] (O32) vs. ([OIII]+[OII])/Hbeta (R23). We also consider a bluer rest-frame "ionization-metallicity" diagram introduced recently to characterize z>10 galaxies: [NeIII]/[OII] vs. ([NeIII]+[OII])/Hdelta; as well as longer-wavelength diagnostic diagrams extending into the rest-frame near-IR: [OIII]/Hbeta vs. [SIII]/[SII] (S32); and HeI/Pagamma and [SIII]/Pagamma vs. [FeII]/Pabeta. With a significant boost in signal-to-noise and large, representative samples of individual galaxy detections, the AURORA emission-line diagrams presented here definitively confirm a physical picture in which chemically-young, alpha-enhanced, massive stars photoionize the ISM in distant galaxies with a harder ionizing spectrum at fixed nebular metallicity than in their z~0 counterparts. We also uncover previously unseen evolution prior to z~2 in the [OIII]/Hbeta vs. [NII]/Halpha diagram, which motivates deep NIRSpec observations at even higher redshift. Finally, we present the first statistical sample of rest-frame near-IR emission-line diagnostics in star-forming galaxies at high redshift. In order to truly interpret rest-frame near-IR line ratios including [FeII], we must obtain better constraints on dust depletion in the high-redshift ISM., Comment: 17 pages, 8 figures, submitted to ApJ

With stunning clarity, JWST has revealed the Universe's first billion years. The scientific community is analyzing a wealth of JWST imaging and spectroscopic data from that era, and is in the process of rewriting the astronomy textbooks. Here, 1.5 years into the JWST science mission, we provide a snapshot of the great progress made towards understanding the initial chapters of our cosmic history. We highlight discoveries and breakthroughs, topics and issues that are not yet understood, and questions that will be addressed in the coming years, as JWST continues its revolutionary observations of the Early Universe. While this compendium is written by a small number of authors, invited to ISSI Bern in March 2024 as part of the 2024 ISSI Breakthrough Workshop, we acknowledge the work of a large community that is advancing our collective understanding of the evolution of the Early Universe., Comment: review article written by the attendees of the 2024 ISSI breakthrough workshop "The first billion year of the Universe", submitted. Comments welcome

In this paper, we describe the "Medium Bands, Mega Science" JWST Cycle 2 survey (JWST-GO-4111) and demonstrate the power of these data to reveal both the spatially-integrated and spatially-resolved properties of galaxies from the local universe to the era of cosmic dawn. Executed in November 2023, MegaScience obtained ~30 arcmin^2 of deep multiband NIRCam imaging centered on the z~0.3 Abell 2744 cluster, including eleven medium-band filters and the two shortest-wavelength broad-band filters, F070W and F090W. Together, MegaScience and the UNCOVER Cycle 1 treasury program provide a complete set of deep (~28-30 mag) images in all NIRCam medium- and broad-band filters. This unique dataset allows us to precisely constrain photometric redshifts, map stellar populations and dust attenuation for large samples of distant galaxies, and examine the connection between galaxy structures and formation histories. MegaScience also includes ~17 arcmin^2 of NIRISS parallel imaging in two broad-band and four medium-band filters from 0.9-4.8um, expanding the footprint where robust spectral energy distribution (SED) fitting is possible. We provide example SEDs and multi-band cutouts at a variety of redshifts, and use a catalog of JWST spectroscopic redshifts to show that MegaScience improves both the scatter and catastrophic outlier rate of photometric redshifts by factors of 2-3. Additionally, we demonstrate the spatially-resolved science enabled by MegaScience by presenting maps of the [OIII] line emission and continuum emission in three spectroscopically-confirmed z>6 galaxies. We show that line emission in reionization-era galaxies can be clumpy, extended, and spatially offset from continuum emission, implying that galaxy assembly histories are complex even at these early epochs. We publicly release fully reduced mosaics and photometric catalogs for both the NIRCam primary and NIRISS parallel fields., Comment: 21 pages, 10 figures. Fully reduced imaging, photometric catalogs, and photometric redshift fits publicly available at https://jwst-uncover.github.io/megascience/

We present an overview and first results from the Spectroscopic Ultradeep Survey Probing Extragalactic Near-infrared Stellar Emission (SUSPENSE), executed with NIRSpec on JWST. The primary goal of the SUSPENSE program is to characterize the stellar, chemical, and kinematic properties of massive quiescent galaxies at cosmic noon. In a single deep NIRSpec/MSA configuration, we target 20 distant quiescent galaxy candidates ($z=1-3$, $H_{AB}\le23$), as well as 53 star-forming galaxies at $z=1-4$. With 16~hr of integration and the G140M-F100LP dispersion-filter combination, we observe numerous Balmer and metal absorption lines for all quiescent candidates. We derive stellar masses (log$M_*/M_{\odot}\sim10.2-11.5$) and detailed star-formation histories (SFHs) and show that all 20 candidate quiescent galaxies indeed have quenched stellar populations. These galaxies show a variety of mass-weighted ages ($0.8-3.3$~Gyr) and star formation timescales ($\sim0.5-4$~Gyr), and four out of 20 galaxies were already quiescent by $z=3$. On average, the $z>1.75$ $[z<1.75]$ galaxies formed 50\% of their stellar mass before $z=4$ $[z=3]$. Furthermore, the typical SFHs of galaxies in these two redshift bins ($z_{\text{mean}}=2.2~[1.3]$) indicate that galaxies at higher redshift formed earlier and over shorter star-formation timescales compared to lower redshifts. Although this evolution is naturally explained by the growth of the quiescent galaxy population over cosmic time, number density calculations imply that mergers and/or late-time star formation also contribute to the evolution. In future work, we will further unravel the early formation, quenching, and late-time evolution of these galaxies by extending this work with studies on their chemical abundances, resolved stellar populations and kinematics., Comment: Accepted in ApJ; 25 pages, 14 figures, 2 tables (excluding appendices)

We use the large spectroscopic data set of the MOSFIRE Deep Evolution Field survey to investigate the kinematics and energetics of ionised gas outflows. Using a sample of 598 star-forming galaxies at redshift 1.4 < $z$ < 3.8, we decompose $\rm{H}\alpha$ and [OIII] emission lines into narrow and broad components, finding significant detections of broad components in 10% of the sample. The ionised outflow velocity from individual galaxies appears independent of galaxy properties, such as stellar mass, star-formation rate (SFR), and star-formation-rate surface density ($\Sigma_{\rm SFR}$). Adopting a simple outflow model, we estimate the mass-, energy- and momentum-loading factors of the ionised outflows, finding modest values with averages of 0.33, 0.04, and 0.22, respectively. The larger momentum- than energy-loading factors, for the adopted physical parameters, imply that these ionised outflows are primarily momentum-driven. We further find a marginal correlation (2.5$\sigma$) between the mass-loading factor and stellar mass in agreement with predictions by simulations, scaling as $\eta_{m}$ $\propto M_{\star}^{-0.45}$. This shallow scaling relation is consistent with these ionised outflows being driven by a combination of mechanical energy generated by supernovae explosions and radiation pressure acting on dusty material. In a majority of galaxies, the outflowing material does not appear to have sufficient velocity to escape the gravitational potential of their host, likely recycling back at later times. Together, these results suggest that the ionised outflows traced by nebular emission lines are negligible, with the bulk of mass and energy carried out in other gaseous phases., Comment: 17 pages, 9 figures, Submitted to Monthly Notices of the Royal Astronomical Society

We present results from the ``Quasar hosts Unveiled by high Angular Resolution Techniques" (QUART) survey studying the Circumgalactic Medium (CGM) by observing rest-frame UV emission lines Ly$\alpha$, C IV and He II around two radio-loud quasars, 3C 9 (z=2.02) and 4C 05.84 (z=2.32), using Keck Cosmic Web Imager (KCWI). We detect large-scale Ly$\alpha$ nebulae around both quasars with projected diameters $\sim$ 100 kpc, with spatially resolved, embedded 15-30 kpc He II and C IV nebulae around both quasars as well as kinematically distinct He II and C IV nebulae at a physical separation of $\sim$ 15 kpc from both quasars. Observations of H$\alpha$, H$\beta$, and [O III] emission using Keck MOSFIRE spectroscopically confirm that the Ly$\alpha$ nebulae extend to companion galaxies and that these quasars are in a protogroup/protocluster environment. We confirm that the He II and C IV emission is kinematically and spatially coincident with the companion galaxies. We estimate the virial masses of the companion galaxies, their metallicities, and star formation rates, and investigate the sources of ionization. We measure the dynamical mass of the host dark matter halos and estimate that the dark matter halos of these systems will grow to a mass of 2 $\times 10^{14}$ M$_{\odot}$ (3C 9) and 2 $\times 10^{13}$ M$_{\odot}$ (4C 05.84) by z=0. The combined CGM and companion galaxies observations indicate Ly$\alpha$ substructure can indicate the presence of companion galaxies in the CGM.

We present the elemental abundances and ages of 19 massive quiescent galaxies at $z\sim1.4$ and $z\sim2.1$ from the Keck Heavy Metal Survey. The ultra-deep LRIS and MOSFIRE spectra were modeled using a full-spectrum stellar population fitting code with variable abundance patterns. The galaxies have iron abundances between [Fe/H] = -0.5 and -0.1 dex, with typical values of $-0.2$ [$-0.3$] at $z\sim1.4$ [$z\sim2.1$]. We also find a tentative $\log\sigma_v$-[Fe/H] relation at $z\sim1.4$. The magnesium-to-iron ratios span [Mg/Fe]$\,=0.1$\,--\,$0.6$ dex, with typical values of $0.3$ [$0.5$] dex at $z\sim1.4$ [$z\sim2.1$]. The ages imply formation redshifts of $z_{\rm form}=2-8$. Compared to quiescent galaxies at lower redshifts, we find [Fe/H] was $\sim0.2$ dex lower at $z=1.4-2.1$. We find no evolution in [Mg/Fe] out to $z\sim1.4$, though the $z\sim2.1$ galaxies are $0.2$ dex enhanced compared to $z=0-0.7$. A comparison of these results to a chemical evolution model indicates that galaxies at higher redshift form at progressively earlier epochs and over shorter star-formation timescales, with the $z\sim2.1$ galaxies forming the bulk of their stars over 150 Myr at $z_{\rm form}\sim4$. This evolution cannot be solely attributed to an increased number of quiescent galaxies at later times; several Heavy Metal galaxies have extreme chemical properties not found in massive galaxies at $z\sim0.0-0.7$. Thus, the chemical properties of individual galaxies must evolve over time. Minor mergers also cannot fully account for this evolution as they cannot increase [Fe/H], particularly in galaxy centers. Consequently, the build-up of massive quiescent galaxies since $z\sim2.1$ may require further mechanisms such as major mergers and/or central star formation., Comment: Published in ApJ

In this paper, we present the Heavy Metal Survey, which obtained ultradeep medium-resolution spectra of 21 massive quiescent galaxies at $1.3

The recent UNCOVER survey with the James Webb Space Telescope (JWST) exploits the nearby cluster Abell 2744 to create the deepest view of our universe to date by leveraging strong gravitational lensing. In this work, we perform photometric fitting of more than 50,000 robustly detected sources out to $z \sim 15$. We show the redshift evolution of stellar ages, star formation rates, and rest-frame colors across the full range of $0.2 \lesssim z \lesssim 15$. The galaxy properties are inferred using the Prospector Bayesian inference framework using informative Prospector-$\beta$ priors on masses and star formation histories to produce joint redshift and stellar population posteriors, and additionally lensing magnification is performed on-the-fly to ensure consistency with the scale-dependent priors. We show that this approach produces excellent photometric redshifts with $\sigma_{\rm NMAD} \sim 0.03$, of a similar quality to the established photometric redshift code EAzY. In line with the open-source scientific objective of the Treasury survey, we publicly release the stellar population catalog with this paper, derived from the photometric catalog adapting aperture sizes based on source profiles. This release includes posterior moments, maximum-likelihood spectra, star-formation histories, and full posterior distributions, offering a rich data set to explore the processes governing galaxy formation and evolution over a parameter space now accessible by JWST., Comment: Corrected typos: Eq.1 should've been (1-kappa)^2, and the lens maps are normalized to D_ds/D_s=1. These errors were only in the writing; no data products or results were affected. The SPS catalogs are accessible via the UNCOVER survey webpage: https://jwst-uncover.github.io/DR2.html#SPSCatalogs, with a copy deposited to Zenodo: https://doi.org/10.5281/zenodo.8401181

We use CEERS JWST/NIRCam imaging to measure rest-frame near-IR light profiles of $>$500 $M_\star>10^{10}~M_\odot$ galaxies in the redshift range $0.510^{11}~M_\odot$) quiescent galaxies between $z=0.5$ and $z=2.3$, again comparing $R_{\rm{opt}}$, \rmass~and \rmassd. We conclude that the main tenets of the size evolution narrative established over the past 20 years, based on rest-frame optical light profile analysis, still hold in the era of JWST/NIRCam observations in the rest-frame near-IR., Comment: Submitted to ApJ. Comments welcome

We report on the discovery of cool gas inflows towards three star-forming galaxies at $\left\sim$ 2.30. Analysis of Keck Low-Resolution Imaging Spectrometer spectroscopy reveals redshifted low-ionisation interstellar (LIS) metal absorption lines with centroid velocities of 60 - 130 km $\rm{s}^{-1}$. These inflows represent some of the most robust detections of inflowing gas into isolated, star-forming galaxies at high redshift. Our analysis suggests that the inflows are due to recycling metal-enriched gas from previous ejections. Comparisons between the galaxies with inflows and a larger parent sample of 131 objects indicate that galaxies with detected inflows may have higher specific star-formation rates (sSFR) and star-formation-rate surface densities. However, when additional galaxies without robustly detected inflows based on centroid velocity but whose LIS absorption line profiles indicate large red-wing velocities are considered, galaxies with inflows do not show unique properties relative to those lacking inflows. Additionally, we calculate the covering fraction of cool inflowing gas as a function of red-wing inflow velocity, finding an enhancement in high sSFR binned galaxies, likely due to an increase in the amount of recycling gas. Together, these results suggest that the low detection rate of galaxies with cool inflows is primarily related to the viewing angle rather than the physical properties of the galaxies., Comment: 10 pages, 7 figures, accepted for publication in MNRAS

Using deep near-infrared Keck/MOSFIRE observations, we analyze the rest-optical spectra of eight star-forming galaxies in the COSMOS and GOODS-N fields. We reach integration times of $\sim$10 hours in the deepest bands, pushing the limits on current ground-based observational capabilities. The targets fall into two redshift bins -- 5 galaxies at $z \sim 1.7$ and 3 at $z \sim 2.5$ -- and were selected as likely to yield significant auroral-line detections. Even with long integration times, detection of the auroral lines remains challenging. We stack the spectra together into subsets based on redshift, improving the signal-to-noise ratio on the [O III] $\lambda 4364$ auroral emission line and, in turn, enabling a direct measurement of the oxygen abundance for each stack. We compare these measurements to commonly-employed strong-line ratios alongside measurements from the literature. We find that the stacks fall within the distribution of $z>1$ literature measurements, but a larger sample size is needed to robustly constrain the relationships between strong-line ratios and oxygen abundance at high redshift. We additionally report detections of [O I] $\lambda6302$ for nine individual galaxies and composite spectra of 21 targets in the MOSFIRE pointings. We plot their line ratios on the [O III] $\lambda 5008$/H$\beta$ vs. [O I] $\lambda 6302$/H$\alpha$ diagnostic BPT diagram, comparing our targets to local galaxies and H II regions. We find that the [O I]/H$\alpha$ ratios in our sample of galaxies are consistent with being produced in gas ionized by $\alpha$-enhanced massive stars, as has been previously inferred for rapidly-forming galaxies at early cosmic times., Comment: 18 pages, 6 figures, submitted to ApJ

We investigate dust attenuation and its dependence on viewing angle for 308 star-forming galaxies at $1.3\leq z\leq2.6$ from the MOSFIRE Deep Evolution Field (MOSDEF) survey. We divide galaxies with a detected H$\alpha$ emission line and coverage of H$\beta$ into eight groups by stellar mass, star formation rate (SFR), and inclination (i.e., axis ratio), then stack their spectra. From each stack, we measure Balmer decrement and gas-phase metallicity, then we compute median \AV and UV continuum spectral slope ($\beta$). First, we find that none of the dust properties (Balmer decrement, \AV, $\beta$) vary with axis ratio. Second, both stellar and nebular attenuation increase with increasing galaxy mass, showing little residual dependence on SFR or metallicity. Third, nebular emission is more attenuated than stellar emission, and this difference grows even larger at higher galaxy masses and SFRs. Based on these results, we propose a three-component dust model where attenuation predominantly occurs in star-forming regions and large, dusty star-forming clumps, with minimal attenuation in the diffuse ISM. In this model, nebular attenuation primarily originates in clumps, while stellar attenuation is dominated by star-forming regions. Clumps become larger and more common with increasing galaxy mass, creating the above mass trends. Finally, we argue that a fixed metal yield naturally leads to mass regulating dust attenuation. Infall of low-metallicity gas increases SFR and lowers metallicity, but leaves dust column density mostly unchanged. We quantify this idea using the Kennicutt-Schmidt and fundamental metallicity relations, showing that galaxy mass is indeed the primary driver of dust attenuation., Comment: 19 pages, 13 figures, accepted for publication in ApJ

We present elemental abundance patterns (C, N, Mg, Si, Ca, Ti, V, Cr, Fe, Co, and Ni) for a population of 135 massive quiescent galaxies at $z\sim0.7$ with ultra-deep rest-frame optical spectroscopy drawn from the LEGA-C survey. We derive average ages and elemental abundances in four bins of stellar velocity dispersion ($\sigma_v$) ranging from 150$~$km$\,$s$^{-1}$ to 250$~$km$\,$s$^{-1}$ using a full-spectrum hierarchical Bayesian model. The resulting elemental abundance measurements are precise to 0.05$\,$dex. The majority of elements, as well as the total metallicity and stellar age, show a positive correlation with $\sigma_v$. Thus, the highest dispersion galaxies formed the earliest and are the most metal-rich. We find only mild or non-significant trends between [X/Fe] and $\sigma_v$, suggesting that the average star-formation timescale does not strongly depend on velocity dispersion. To first order, the abundance patterns of the $z\sim0.7$ quiescent galaxies are strikingly similar to those at $z\sim0$. However, at the lowest velocity dispersions the $z\sim0.7$ galaxies have slightly enhanced N, Mg, Ti, and Ni abundance ratios and earlier formation redshifts than their $z\sim0$ counterparts. Thus, while the higher-mass quiescent galaxy population shows little evolution, the low-mass quiescent galaxies population has grown significantly over the past six billion years. Finally, the abundance patterns of both $z\sim0$ and $z\sim0.7$ quiescent galaxies differ considerably from theoretical prediction based on a chemical evolution model, indicating that our understanding of the enrichment histories of these galaxies is still very limited., Comment: 24 pages, 12 figures, accepted for publication in ApJ

We use the large spectroscopic dataset of the MOSFIRE Deep Evolution Field (MOSDEF) survey to investigate some of the key factors responsible for the elevated ionization parameters (U) inferred for high-redshift galaxies, focusing in particular on the role of star-formation-rate surface density (Sigma_SFR). Using a sample of 317 galaxies with spectroscopic redshifts z~1.9-3.7, we construct composite rest-frame optical spectra in bins of Sigma_SFR and infer electron densities, n_e, using the ratio of the [OII] 3727, 3730 doublet. Our analysis suggests a significant (~3 sigma) correlation between n_e and Sigma_SFR. We further find significant correlations between U and Sigma_SFR for composite spectra of a subsample of 113 galaxies, and for a smaller sample of 25 individual galaxies with inferences of U. The increase in n_e -- and possibly also the volume filling factor of dense clumps in HII regions -- with Sigma_SFR appear to be important factors in explaining the relationship between U and Sigma_SFR. Further, the increase in n_e and SFR with redshift at a fixed stellar mass can account for most of the redshift evolution of U. These results suggest that the gas density, which sets n_e and the overall level of star-formation activity, may play a more important role than metallicity evolution in explaining the elevated ionization parameters of high-redshift galaxies., Comment: 11 pages, 9 figures, 1 table, submitted to ApJ

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., Comment: 28 pages, 19 figures, resubmitted to ApJS following significant data product improvements. Comments welcome. Catalogs can be accessed at https://jwst-uncover.github.io/DR2.html#PhotometricCatalogs

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, with repeat visits in summer 2024. 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., Comment: 19 pages, 8 figures, 4 tables, Accepted for publication in ApJ

We present visual classifications of merger-induced tidal disturbances in 143 $\rm{M}_* \sim 10^{11}\rm{M}_\odot$ post-starburst galaxies at z$\sim$0.7 identified in the SQuIGG$\vec{L}$E Sample. This sample spectroscopically selects galaxies from the Sloan Digital Sky Survey that have stopped their primary epoch of star formation within the past $\sim$500 Myrs. Visual classifications are performed on Hyper Suprime Cam (HSC) i-band imaging. We compare to a control sample of mass- and redshift-matched star-forming and quiescent galaxies from the Large Early Galaxy Census and find that post-starburst galaxies are more likely to be classified as disturbed than either category. This corresponds to a factor of $3.6^{+2.9}_{-1.3}$ times the disturbance rate of older quiescent galaxies and $2.1^{+1.9}_{-.73}$ times the disturbance rate of star-forming galaxies. Assuming tidal features persist for $\lesssim500$ Myr, this suggests merging is coincident with quenching in a significant fraction of these post-starbursts. Galaxies with tidal disturbances are younger on average than undisturbed post-starburst galaxies in our sample, suggesting tidal features from a major merger may have faded over time. This may be exacerbated by the fact that, on average, the undisturbed subset is fainter, rendering low surface brightness tidal features harder to identify. However, the presence of ten young ($\lesssim150$ Myr since quenching) undisturbed galaxies suggests that major mergers are not the only fast physical mechanism that shut down the primary epoch of star formation in massive galaxies at intermediate redshift., Comment: 13 pages, 8 figures, accepted to ApJ

Observations and simulations have demonstrated that star formation in galaxies must be actively suppressed to prevent the formation of over-massive galaxies. Galactic outflows driven by stellar feedback or supermassive black hole accretion are often invoked to regulate the amount of cold molecular gas available for future star formation, but may not be the only relevant quenching processes in all galaxies. We present the discovery of vast molecular tidal features extending up to 64 kpc outside of a massive z=0.646 post-starburst galaxy that recently concluded its primary star-forming episode. The tidal tails contain (1.2 +/- 0.1)x10^10 Msun of molecular gas, 47 +/- 5 % of the total cold gas reservoir of the system. Both the scale and magnitude of the molecular tidal features are unprecedented compared to all known nearby or high-redshift merging systems. We infer that the cold gas was stripped from the host galaxies during the merger, which is most likely responsible for triggering the initial burst phase and the subsequent suppression of star formation. While only a single example, this result shows that galaxy mergers can regulate the cold gas contents in distant galaxies by directly removing a large fraction of the molecular gas fuel, and plausibly suppress star formation directly, a qualitatively different physical mechanism than feedback-driven outflows., Comment: Published in ApJL, 8 pages, 5 figures

The $\rm{H}\alpha$-to-UV luminosity ratio ($L(\rm H\alpha)/L(\rm UV)$) is often used to probe SFHs of star-forming galaxies and it is important to validate it against other proxies for burstiness. To address this issue, we present a statistical analysis of the resolved distribution of $\Sigma_{\rm{SFR}}$ as well as stellar age and their correlations with the globally measured $L(\rm H\alpha)/L(\rm UV)$ for a sample of 310 star-forming galaxies in two redshift bins of $1.37 < z < 1.70$ and $ 2.09 < z < 2.61$ observed by the MOSDEF survey. We use the multi-waveband CANDELS/3D-HST imaging of MOSDEF galaxies to construct $\Sigma_{\rm{SFR}}$ and stellar age maps. We analyze the composite rest-frame far-UV spectra of a subsample of MOSDEF targets obtained by the Keck/LRIS, which includes 124 star-forming galaxies (MOSDEF-LRIS) at redshifts $1.4 < z < 2.6$, to examine the average stellar population properties, and the strength of age-sensitive FUV spectral features in bins of $L(\rm H\alpha)/L(\rm UV)$. Our results show no significant evidence that individual galaxies with higher $L(\rm H\alpha)/L(\rm UV)$ are undergoing a burst of star formation based on the resolved distribution of $\Sigma_{\rm{SFR}}$ of individual star-forming galaxies. We segregate the sample into subsets with low and high $L(\rm H\alpha)/L(\rm UV)$. The high-$L(\rm H\alpha)/L(\rm UV)$ subset exhibits, on average, an age of $\log[\rm{Age/yr}]$ = 8.0, compared to $\log[\rm{Age/yr}]$ = 8.4 for the low-$L(\rm H\alpha)/L(\rm UV)$ galaxies, though the difference in age is significant at only the $2\sigma$ level. Furthermore, we find no variation in the strengths of Siiv$\lambda\lambda1393, 1402$ and Civ$\lambda\lambda1548, 1550$ P-Cygni features from massive stars between the two subsamples., Comment: 16 pages, 10 figures, published by the Monthly Notices of the Royal Astronomical Society

We define a new morphology metric called "patchiness" ($P$) that is sensitive to deviations from the average of a resolved distribution, does not require the galaxy center to be defined, and can be used on the spatially-resolved distribution of any galaxy property. While the patchiness metric has a broad range of applications, we demonstrate its utility by investigating the distribution of dust in the interstellar medium of 310 star-forming galaxies at spectroscopic redshifts $1.36

We present ultra-deep Keck/MOSFIRE rest-optical spectra of two star-forming galaxies at z=2.18 in the COSMOS field with bright emission lines, representing more than 20~hours of total integration. The fidelity of these spectra enabled the detection of more than 20 unique emission lines for each galaxy, including the first detection of the auroral [O II]$\lambda\lambda$7322,7332 lines at high redshift. We use these measurements to calculate the electron temperature in the low-ionization O$^+$ zone of the ionized ISM and derive abundance ratios of O/H, N/H, and N/O using the direct method. The N/O and $\alpha$/Fe abundance patterns of these galaxies are consistent with rapid formation timescales and ongoing strong starbursts, in accord with their high specific star-formation rates. These results demonstrate the feasibility of using auroral [O II] measurements for accurate metallicity studies at high redshift in a higher metallicity regime previously unexplored with the direct method in distant galaxies. These results also highlight the difficulty in obtaining the measurements required for direct-method metallicities from the ground. We emphasize the advantages that the JWST/NIRSpec instrument will bring to high-redshift metallicity studies, where the combination of increased sensitivity and uninterrupted wavelength coverage will yield more than an order of magnitude increase in efficiency for multiplexed auroral-line surveys relative to current ground-based facilities. Consequently, the advent of JWST promises to be the beginning of a new era of precision chemical abundance studies of the early universe at a level of detail rivaling that of local galaxy studies., Comment: 18 pages, 5 figures, 3 tables, submitted to ApJ

Accurate models of the star formation histories (SFHs) of recently-quenched galaxies can provide constraints on when and how galaxies shut down their star formation. The recent development of "non-parametric" SFH models promises the flexibility required to make these measurements. However, model and prior choices significantly affect derived SFHs, particularly for post-starburst galaxies (PSBs) which have sharp changes in their recent SFH. In this paper, we create mock PSBs, then use the Prospector SED fitting software to test how well four different SFH models recover key properties. We find that a two-component parametric model performs well for our simple mock galaxies, but is sensitive to model mismatches. The fixed- and flexible-bin non-parametric models included in Prospector are able to rapidly quench a major burst of star formation, but systematically underestimate the post-burst age by up to 200 Myr. We develop a custom SFH model that allows for additional flexibility in the recent SFH. Our flexible non-parametric model is able to constrain post-burst ages with no significant offset and just ~90 Myr of scatter. Our results suggest that while standard non-parametric models are able to recover first-order quantities of the SFH (mass, SFR, average age), accurately recovering higher-order quantities (burst fraction, quenching time) requires careful consideration of model flexibility. These mock recovery tests are a critical part of future SFH studies. Finally, we show that our new, public SFH model is able to accurately recover the properties of mock star-forming and quiescent galaxies and is suitable for broader use in the SED fitting community., Comment: 24 pages, 10 figures. Posted after referee report; comments welcome. Key results in Figures 8 & 9. New SFH model publicly available as "continuity_psb_sfh" in Prospector: https://github.com/bd-j/prospector

We analyze the completeness of the MOSDEF survey, in which z ~ 2 galaxies were selected for rest-optical spectroscopy from well-studied HST extragalactic legacy fields down to a fixed rest-optical magnitude limit (H_AB = 24.5). The subset of z ~ 2 MOSDEF galaxies with high signal-to-noise (S/N) emission-line detections analyzed in previous work represents a small minority (<10%) of possible z ~ 2 MOSDEF targets. It is therefore crucial to understand how representative this high S/N subsample is, while also more fully exploiting the MOSDEF spectroscopic sample. Using spectral-energy-distribution (SED) models and rest-optical spectral stacking, we compare the MOSDEF z ~ 2 high S/N subsample with the full MOSDEF sample of z ~ 2 star-forming galaxies with redshifts, the latter representing an increase in sample size of more than a factor of three. We find that both samples have similar emission-line properties, in particular in terms of the magnitude of the offset from the local star-forming sequence on the [N II] BPT diagram. There are small differences in median host galaxy properties, including the stellar mass (M_*), star-formation rate (SFR) and specific SFR (sSFR), and UVJ colors; however, these offsets are minor considering the wide spread of the distributions. Using SED modeling, we also demonstrate that the sample of z ~ 2 star-forming galaxies observed by the MOSDEF survey is representative of the parent catalog of available such targets. We conclude that previous MOSDEF results on the evolution of star-forming galaxy emission-line properties were unbiased relative to the parent z ~ 2 galaxy population., Comment: 18 pages, 10 figures, 3 tables

We present a detailed study of a galaxy merger taking place at $z=1.89$ in the GOODS-S field. Here we analyze Keck/MOSFIRE spectroscopic observations from the MOSFIRE Deep Evolution Field (MOSDEF) survey along with multi-wavelength photometry assembled by the 3D-HST survey. The combined dataset is modeled to infer the past star-formation histories (SFHs) of both merging galaxies. They are found to be massive, with log$_{10}(M_{\ast}/M_{\odot}) > 11$, with a close mass ratio satisfying the typical major-merger definition. Additionally, in the context of delayed-$\tau$ models, GOODS-S 43114 and GOODS-S 43683 have similar SFHs and low star-formation rates (log$_{10}$(SFR(SED)/$M_{\odot}/\rm{yr}^{-1}$) $<$ 1.0) compared to their past averages. The best-fit model SEDs show elevated H$\delta_{\rm{A}}$ values for both galaxies, indicating that their stellar spectra are dominated by A-type stars, and that star formation peaked $\sim0.5-1$ Gyr ago and has recently declined. Additionally, based on SED fitting both merging galaxies turned on and shut off star formation within a few hundred Myr of each other, suggesting that their bursts of star formation may be linked. Combining the SFHs and H$\delta_{\rm{A}}$ results with recent galaxy merger simulations, we infer that these galaxies have recently completed their first pericentric passage and are moving apart. Finally, the relatively low second velocity moment of GOODS-S 43114 given its stellar mass, suggests a disk-like structure. However, including the geometry of the galaxy in the modeling does not completely resolve the discrepancy between the dynamical and stellar masses. Future work is needed to resolve this inconsistency in mass., Comment: 12 pages, 7 figures, 1 table, Accepted for publication in MNRAS

We aim to quantify the relation between the dust-to-gas mass ratio (DTG) and gas-phase metallicity of $z=$2.1-2.5 luminous galaxies and contrast this high-redshift relation against analogous constraints at z$=$0. We present a sample of ten star-forming main-sequence galaxies in the redshift range $2.1

We present observations of CO(3-2) in 13 main-sequence $z=2.0-2.5$ star-forming galaxies at $\log(M_*/M_{\odot})=10.2-10.6$ that span a wide range in metallicity (O/H) based on rest-optical spectroscopy. We find that CO(3-2)/SFR decreases with decreasing metallicity, implying that the CO luminosity per unit gas mass is lower in low-metallicity galaxies at $z\sim2$. We constrain the CO-to-H$_2$ conversion factor ($\alpha_{\text{CO}}$) and find that $\alpha_{\text{CO}}$ inversely correlates with metallicity at $z\sim2$. We derive molecular gas masses ($M_{\text{mol}}$) and characterize the relations among $M_*$, SFR, $M_{\text{mol}}$, and metallicity. At $z\sim2$, $M_{\text{mol}}$ increases and molecular gas fraction ($M_{\text{mol}}$/$M_*$) decrease with increasing $M_*$, with a significant secondary dependence on SFR. Galaxies at $z\sim2$ lie on a near-linear molecular KS law that is well-described by a constant depletion time of 700 Myr. We find that the scatter about the mean SFR-$M_*$, O/H-$M_*$, and $M_{\text{mol}}$-$M_*$ relations is correlated such that, at fixed $M_*$, $z\sim2$ galaxies with larger $M_{\text{mol}}$ have higher SFR and lower O/H. We thus confirm the existence of a fundamental metallicity relation at $z\sim2$ where O/H is inversely correlated with both SFR and $M_{\text{mol}}$ at fixed $M_*$. These results suggest that the scatter of the $z\sim2$ star-forming main sequence, mass-metallicity relation, and $M_{\text{mol}}$-$M_*$ relation are primarily driven by stochastic variations in gas inflow rates. We place constraints on the mass loading of galactic outflows and perform a metal budget analysis, finding that massive $z\sim2$ star-forming galaxies retain only 30% of metals produced, implying that a large mass of metals resides in the circumgalactic medium., Comment: 35 pages, 17 figures, submitted to ApJ

We present structural measurements of 145 spectroscopically selected intermediate-redshift (z$\sim$0.7), massive ($M_\star \sim 10^{11} \ M_\odot$) post-starburst galaxies from the SQuIGG$\vec{L}$E Sample measured using wide-depth Hyper Suprime-Cam i-band imaging. This deep imaging allows us to probe the sizes and structures of these galaxies, which we compare to a control sample of star forming and quiescent galaxies drawn from the LEGA-C Survey. We find that post-starburst galaxies systematically lie $\sim0.1$ dex below the quiescent mass-size (half-light radius) relation, with a scatter of $\sim0.2$ dex. This finding is bolstered by non-parametric measures, such as the Gini coefficient and the concentration, which also reveal these galaxies to have more compact light profiles than both quiescent and star-forming populations at similar mass and redshift. The sizes of post-starburst galaxies show either negative or no correlation with the time since quenching, such that more recently quenched galaxies are larger or similarly sized. This empirical finding disfavors the formation of post-starburst galaxies via a purely central burst of star formation that simultaneously shrinks the galaxy and shuts off star formation. We show that the central densities of post-starburst and quiescent galaxies at this epoch are very similar, in contrast with their effective radii. The structural properties of z$\sim$0.7 post-starburst galaxies match those of quiescent galaxies that formed in the early universe, suggesting that rapid quenching in the present epoch is driven by a similar mechanism to the one at high redshift., Comment: 28 pages, 19 figures, 2 appendices, updated to accepted ApJ version

We present results from ALMA 1.2mm continuum observations of a sample of 27 star-forming galaxies at z=2.1-2.5 from the MOSFIRE Deep Evolution Field (MOSDEF) survey. These galaxies have gas-phase metallicity and star-formation rate measurements from Hb, [OIII], Ha, and [NII]. Using stacks of Spitzer, Herschel, and ALMA photometry (rest-frame ~ 8-400$\mu$m), we examine the IR SED of high-redshift subsolar metallicity (~0.5 $Z_{\odot}$) LIRGs. We find that the data agree well with an average SED template of higher luminosity local low-metallicity dwarf galaxies (reduced $\chi^2$ of 1.8). When compared with the commonly used templates for solar-metallicity local galaxies or high-redshift LIRGs and ULIRGs, even in the most favorable case (with reduced $\chi^2$ of 2.8), the templates are rejected at >98% confidence level. The broader and hotter IR SED of both the local dwarfs and high-redshift subsolar metallicity galaxies may result from different grain properties, a clumpy dust geometry, or a harder/more intense ionizing radiation field that heats the dust to higher temperatures. The obscured SFR indicated by the FIR emission of the subsolar metallicity galaxies is only ~ 60% of the total SFR, which is considerably lower than that of the local LIRGs with ~ 96-97% obscured fractions. Due to the evolving IR SED shape, the local LIRG templates fit to mid-IR data can overestimate the Rayleigh-Jeans tail measurements at z~2 by a factor of 2-20, and these templates underestimate IR luminosities if fit to the observed ALMA fluxes by >0.4dex. At a given stellar mass or metallicity, dust masses at z~2.3 are an order of magnitude higher than those at z~0. Given the predicted molecular gas mass fractions, the observed z~2.3 dust-to-stellar mass ratios suggest lower dust-to-molecular gas masses than in local galaxies at the same metallicity., Comment: Accepted for publication in ApJ. 29 pages, 2 appendices, 10 figures, 3 tables

The combination of the MOSDEF and KBSS-MOSFIRE surveys represents the largest joint investment of Keck/MOSFIRE time to date, with ~3000 galaxies at 1.4<=z<=3.8, roughly half of which are at z~2. MOSDEF is photometric- and spectroscopic-redshift selected with a rest-optical magnitude limit, while KBSS-MOSFIRE is primarily selected based on rest-UV colors and a rest-UV magnitude limit. Analyzing both surveys in a uniform manner with consistent spectral-energy-distribution (SED) models, we find that the MOSDEF z~2 targeted sample has a higher median M_* and redder rest U-V color than the KBSS-MOSFIRE z~2 targeted sample, and a smaller median SED-based SFR and sSFR (SFR(SED) and sSFR(SED)). Specifically, MOSDEF targeted a larger population of red galaxies with U-V and V-J >=1.25, while KBSS-MOSFIRE contains more young galaxies with intense star formation. Despite these differences in the z~2 targeted samples, the subsets of the surveys with multiple emission lines detected and analyzed in previously published work are much more similar. All median host-galaxy properties with the exception of stellar population age -- i.e., M_*, SFR(SED), sSFR(SED), A_V, and UVJ colors -- agree within the uncertainties. Additionally, when uniform emission-line fitting and stellar Balmer absorption correction techniques are applied, there is no significant offset between the two samples in the [OIII]$\lambda$5008/H$\beta$ vs. [NII]$\lambda$6585/H$\alpha$ diagnostic diagram, in contrast to previously-reported discrepancies. We can now combine the MOSDEF and KBSS-MOSFIRE surveys to form the largest z~2 sample with moderate-resolution rest-optical spectra and construct the fundamental scaling relations of star-forming galaxies during this important epoch., Comment: 23 pages, 14 figures, published in MNRAS

We describe the SQuIGGLE survey of intermediate-redshift post-starburst galaxies. We leverage the large sky coverage of the SDSS to select ~1300 recently-quenched galaxies at 0.575% of SQuIGGLE galaxies formed at least a quarter of their total stellar mass in the recent burst, which ended just ~200Myr before observation. We find that SQuIGGLE galaxies are on average younger and more burst-dominated than most other z<~1 post-starburst samples. This large sample of bright post-starburst galaxies at intermediate redshift opens a wide range of studies into the quenching process. In particular, the full SQuIGGLE survey will investigate the molecular gas reservoirs, morphologies, kinematics, resolved stellar populations, AGN incidence, and infrared properties of this unique sample of galaxies in order to place definitive constraints on the quenching process., Comment: 23 pages, 16 figures, accepted to ApJ

We use ALMA observations of CO(2-1) in 13 massive ($M_{\star}\gtrsim 10^{11} M_{\odot}$) post-starburst galaxies at $z\sim0.6$ to constrain the molecular gas content in galaxies shortly after they quench their major star-forming episode. The post-starburst galaxies in this study are selected from the Sloan Digital Sky Survey spectroscopic samples (DR14) based on their spectral shapes, as part of the SQuIGGLE program. Early results showed that two post-starburst galaxies host large H$_2$ reservoirs despite their low inferred star formation rates. Here we expand this analysis to a larger statistical sample of 13 galaxies. Six of the primary targets (45%) are detected, with $M_{H_2}\gtrsim10^9 M_{\odot}$. Given their high stellar masses, this mass limit corresponds to an average gas fraction of $\langle f_{H_2} \equiv M_{H_2}/M_{\star} \rangle \sim7\%$, or ${\sim}14\%$ using lower stellar masses estimates derived from analytic, exponentially declining star formation histories. The gas fraction correlates with the $D_n4000$ spectral index, suggesting that the cold gas reservoirs decrease with time since burst, as found in local K+A galaxies. Star formation histories derived from flexible stellar population synthesis modeling support this empirical finding: galaxies that quenched $\lesssim 150$ Myr prior to observation host detectable CO(2-1) emission, while older post-starburst galaxies are undetected. The large $\mathrm{H_2}$ reservoirs and low star formation rates in the sample imply that the quenching of star formation precedes the disappearance of the cold gas reservoirs. However, within the following 100-200 Myrs, the SQuIGGLE galaxies require the additional and efficient heating or removal of cold gas to bring their low star formation rates in line with standard $\mathrm{H_2}$ scaling relations., Comment: 20 pages, 13 figures, accepted for publication in ApJ

We present the $H_{160}$ morphological catalogs for the COSMOS-DASH survey, the largest area near-IR survey using HST-WFC3 to date. Utilizing the "Drift And SHift" observing technique for HST-WFC3 imaging, the COSMOS-DASH survey imaged approximately 0.5 deg$^2$ of the UltraVISTA deep stripes (0.7 deg$^2$ when combined with archival data). Global structural parameters are measured for 51,586 galaxies within COSMOS-DASH using GALFIT (excluding the CANDELS area) with detection using a deep multi-band HST image. We recover consistent results with those from the deeper 3D-HST morphological catalogs, finding that, in general, sizes and S\'ersic indices of typical galaxies are accurate to limiting magnitudes of $H_{160}<23$ and $H_{160}<22$ ABmag, respectively. In size-mass parameter space, galaxies in COSMOS-DASH demonstrate robust morphological measurements out to $z\sim2$ and down to $\log(M_\star/M_\odot)\sim9$. With the advantage of the larger area of COSMOS-DASH, we measure a flattening of the quiescent size-mass relation below $\log(M_\star/M_\odot)\sim10.5$ that persists out to $z\sim2$. We show that environment is not the primary driver of this flattening, at least out to $z=1.2$, whereas internal physical processes may instead govern the structural evolution., Comment: 27 pages, 17 figures. Accepted for publication in ApJ. For associated morphological catalog, see https://archive.stsci.edu/hlsp/cosmos-dash

We investigate the relationship between dust attenuation and stellar mass ($M_*$) in star-forming galaxies over cosmic time. For this analysis, we compare measurements from the MOSFIRE Deep Evolution Field (MOSDEF) survey at $z\sim2.3$ and the Sloan Digital Sky Survey (SDSS) at $z\sim0$, augmenting the latter optical dataset with both UV Galaxy Evolution Explorer (GALEX) and mid-infrared Wide-field Infrared Survey Explorer (WISE) photometry from the GALEX-SDSS-WISE Catalog. We quantify dust attenuation using both spectroscopic measurements of H$\alpha$ and H$\beta$ emission lines, and photometric measurements of the rest-UV stellar continuum. The H$\alpha$/H$\beta$ ratio is used to determine the magnitude of attenuation at the wavelength of H$\alpha$, $A_{{\rm H}\alpha}$. Rest-UV colors and spectral-energy-distribution fitting are used to estimate $A_{1600}$, the magnitude of attenuation at a rest wavelength of 1600\AA. As in previous work, we find a lack of significant evolution in the relation between dust attenuation and $M_*$ over the redshift range $z\sim0$ to $z\sim2.3$. Folding in the latest estimates of the evolution of $M_{{\rm dust}}$, $({M_{{\rm dust}}}/{M_{{\rm gas}}})$, and gas surface density at fixed $M_*$, we find that the expected $M_{{\rm dust}}$ and dust mass surface density are both significantly higher at $z\sim2.3$ than at $z\sim0$. These differences appear at odds with the lack of evolution in dust attenuation. To explain the striking constancy in attenuation vs. $M_*$, it is essential to determine the relationship between metallicity and $({M_{{\rm dust}}}/{M_{{\rm gas}}})$, the dust mass absorption coefficient, and dust geometry, and the evolution of these relations and quantities from $z\sim0$ to $z\sim2.3$., Comment: 14 pages, 4 figures, accepted to ApJ

We perform an aperture-matched analysis of dust-corrected H$\alpha$ and UV SFRs using 303 star-forming galaxies with spectroscopic redshifts $1.36

Over the past decade, rest-frame color-color diagrams have become popular tools for selecting quiescent galaxies at high redshift, breaking the color degeneracy between quiescent and dust-reddened star-forming galaxies. In this work, we study one such color-color selection tool -- the rest-frame $U-V$ vs. $V-J$ diagram -- by employing mock observations of cosmological galaxy formation simulations. In particular, we conduct numerical experiments assessing both trends in galaxy properties in UVJ space and the color-color evolution of massive galaxies as they quench at redshifts $z\sim 1$--$2$. We find that our models broadly reproduce the observed UVJ diagram at $z=1$--$2$, including (for the first time in a cosmological simulation) reproducing the population of extremely dust-reddened galaxies in the top right of the UVJ diagram. However, our models primarily populate this region with low-mass galaxies and do not produce as clear a bimodality between star-forming and quiescent galaxies as is seen in observations. The former issue is due to an excess of dust in low-mass galaxies and relatively gray attenuation curves in high-mass galaxies, while the latter is due to the overpopulation of the green valley in SIMBA. When investigating the time evolution of galaxies on the UVJ diagram, we find that the quenching pathway on the UVJ diagram is independent of the quenching timescale, and instead dependent primarily on the average specific star formation rate in the 1 Gyr prior to the onset of quenching. Our results support the interpretation of different quenching pathways as corresponding to the divergent evolution of post-starburst and green valley galaxies., Comment: Accepted to ApJ

We present elemental abundances and stellar population ages for 68 massive quiescent galaxies at $0.59\leq z\leq0.75$ from the LEGA-C survey. The abundance patterns and ages, derived from full-spectrum modeling, are examined as a function of stellar mass ($M_*$) and size (i.e., half-light radius; $R_e$). We find that both [Mg/H] and [Fe/H] do not vary with stellar mass but are correlated with $M_*/R_e$ for quiescent galaxies with $M_*>10^{10.5} M_\odot$. Thus, at fixed mass, compact quiescent galaxies are on average more metal rich. This result reinforces the picture that supernova feedback and gravitational potential regulate chemical enrichment. [Mg/Fe] does not vary with $M_*$ or $M_*/R_e$, but there is a marginal positive relation between age and mass. Our results support low-redshift findings that more massive galaxies form their stars at earlier times. However, in contrast to low-redshift studies, star formation timescale does not appear to depend on mass or size. We also compare the mass-[Fe/H] and mass-[Mg/H] relations to stacks of quiescent galaxies at $z\sim0$ and find that both relations increase by $\sim0.2$ dex over the past 7 Gyr. Furthermore, at $z\sim0.7$ we find a clear trend with age, such that older quiescent galaxies have lower metallicities. Both results can be explained by a chemical evolution model in which galaxies quench via gas removal. Future work, in particular with JWST/NIRSpec, will extend this analysis to higher redshifts, allowing us to fully exploit abundance patterns to study the formation histories of quiescent galaxies.

The complex structure of gas, metals, and dust in the interstellar and circumgalactic medium (ISM and CGM, respectively) in star-forming galaxies can be probed by Ly$\alpha$ emission and absorption, low-ionization interstellar (LIS) metal absorption, and dust reddening E(B-V). We present a statistical analysis of the mutual correlations among Ly$\alpha$ equivalent width (EW$_{Ly\alpha}$), LIS equivalent width (EW$_{LIS}$), and E(B-V) in a sample of 157 star-forming galaxies at $z\sim2.3$. With measurements obtained from individual, deep rest-UV spectra and spectral-energy distribution (SED) modeling, we find that the tightest correlation exists between EW$_{LIS}$ and E(B-V), although correlations among all three parameters are statistically significant. These results signal a direct connection between dust and metal-enriched HI gas, and that they are likely co-spatial. By comparing our results with the predictions of different ISM/CGM models, we favor a dusty ISM/CGM model where dust resides in HI gas clumps and Ly$\alpha$ photons escape through the low HI covering fraction/column density intra-clump medium. Finally, we investigate the factors that potentially contribute to the intrinsic scatter in the correlations studied in this work, including metallicity, outflow kinematics, Ly$\alpha$ production efficiency, and slit loss. Specifically, we find evidence that scatter in the relationship between EW$_{Ly\alpha}$ and E(B-V) reflects the variation in metal-to-HI covering fraction ratio as a function of metallicity, and the effects of outflows on the porosity of the ISM/CGM. Future simulations incorporating star-formation feedback and the radiative transfer of Ly$\alpha$ photons will provide key constraints on the spatial distributions of neutral hydrogen gas and dust in the ISM/CGM structure., Comment: 19 pages, 6 figures, 3 tables, accepted for publication in ApJ

We analyze the rest-optical emission-line ratios of z~1.5 galaxies drawn from the MOSFIRE Deep Evolution Field (MOSDEF) survey. Using composite spectra we investigate the mass-metallicity relation (MZR) at z~1.5 and measure its evolution to z=0. When using gas-phase metallicities based on the N2 line ratio, we find that the MZR evolution from z~1.5 to z=0 depends on stellar mass, evolving by $\Delta\rm log(\rm O/H)\sim0.25$ dex at $M_*<10^{9.75}M_{\odot}$ down to $\Delta\rm log(\rm O/H)\sim0.05$ at $M_*>10^{10.5}M_{\odot}$. In contrast, the O3N2-based MZR shows a constant offset of $\Delta\rm log(\rm O/H)\sim0.30$ across all masses, consistent with previous MOSDEF results based on independent metallicity indicators, and suggesting that O3N2 provides a more robust metallicity calibration for our z~1.5 sample. We investigated the secondary dependence of the MZR on SFR by measuring correlated scatter about the mean $M_*$-specific SFR and $M_*-\log(\rm O3N2)$ relations. We find an anti-correlation between $\log(\rm O/H)$ and sSFR offsets, indicating the presence of a $M_*$-SFR-Z relation, though with limited significance. Additionally, we find that our z~1.5 stacks lie along the z=0 metallicity sequence at fixed $\mu=\log(M_*/M_{\odot})-0.6\times\log(\rm SFR / M_{\odot} yr^{-1})$ suggesting that the z~1.5 stacks can be described by the z=0 fundamental metallicity relation (FMR). However, using different calibrations can shift the calculated metallicities off of the local FMR, indicating that appropriate calibrations are essential for understanding metallicity evolution with redshift. Finally, understanding how [NII]/H$\alpha$ scales with galaxy properties is crucial to accurately describe the effects of blended [NII] and H$\alpha$ on redshift and H$\alpha$ flux measurements in future large surveys utilizing low-resolution spectra such as with Euclid and the Roman Space Telescope., Comment: 14 Pages, 9 figures, Accepted to MNRAS

We study how half-mass radii, central mass densities ($\Sigma_1$), and color gradients change as galaxies evolve. We separate $\sim7,000$ galaxies into sixteen groups with similar spectral shapes; each group represents a different evolutionary stage. We find that different galaxy types populate different regions of both size-mass and $\Sigma_1$-mass space. The nine star-forming groups lie along the integrated star-forming $\Sigma_1$-mass relation. However, these star-forming groups form steep parallel relations in the size-mass plane, with slopes similar to the quiescent size-mass relation. These steep slopes can be explained as a transformation of the star-forming $\Sigma_1$-mass relation and its scatter. We identify three types of transitional galaxies. Green valley and post-starburst galaxies are similarly compact at $z>1.5$; however, their distinct color gradients indicate that the two populations represent different pathways to quenching. Post-starburst galaxies have flat color gradients and compact structures, consistent with a fast quenching pathway which requires structural change and operates primarily at high redshift. Green valley galaxies have negative color gradients, and are both larger and more numerous towards lower redshift. These galaxies are consistent with slow quenching without significant structural change. We find that dusty star-forming galaxies at $z\gtrsim2$ are very compact, and may represent the "burst" before post-starburst galaxies; at $z\lesssim2$, dusty star-forming galaxies are extended and have shallow color gradients consistent with slow quenching. Our results suggest that star-forming galaxies grow gradually up the \sig-mass relation until (a) they naturally reach the high $\Sigma_1$ values required for quiescence, or (b) a compaction-type event rapidly increases their $\Sigma_1$., Comment: 27 pages, 13 figures, accepted to ApJ. Key results in Figures 10, 11, 12