Search

The mass–metallicity relation provides crucial insights into the baryon cycle in galaxies and strong constraints on galaxy formation models. We use JWST NIRSpec observations from the UNCOVER program to measure the gas-phase metallicity in a sample of eight galaxies during the epoch of reionization at z = 6–8. Thanks to the strong lensing of the galaxy cluster Abell 2744, we are able to probe extremely low stellar masses between 10 ^6 and 10 ^8 M _⊙ . Using strong-line diagnostics and the most recent JWST calibrations, we derive extremely low oxygen abundances in the range of 12 + log(O/H) = 6.7–7.8. By combining this sample with more massive galaxies at similar redshifts, we derive a best-fit relation of 12 + log(O/H) = $-{0.076}_{-0.03}^{+0.03}\times {(\mathrm{log}({M}_{\star }))}^{2}+{1.61}_{-0.52}^{+0.52}$ × $\mathrm{log}({M}_{\star })-{0.26}_{-0.10}^{+0.10}$ , which becomes steeper than determinations at z ∼ 3–6 toward low-mass galaxies. Our results show a clear redshift evolution in the overall normalization of the relation, galaxies at higher redshift having significantly lower metallicities at a given mass. A comparison with theoretical models provides important constraints on which physical processes, such as metal mixing, star formation or feedback recipes, are important in reproducing the observations. Additionally, these galaxies exhibit star formation rates that are higher by a factor of a few to tens compared to extrapolated relations at similar redshifts or theoretical predictions of main-sequence galaxies, pointing to a recent burst of star formation. All these observations are indicative of the highly stochastic star formation and interstellar medium enrichment expected in these low-mass systems, suggesting that feedback mechanisms in high- z dwarf galaxies might be different from those in place at higher masses.

It is well known that almost all isolated dwarf galaxies are actively forming stars. We report the discovery of dw1322m2053 (nicknamed Hedgehog), an isolated quiescent dwarf galaxy at a distance of 2.40 ± 0.15 Mpc with a stellar mass of M _⋆ ≈ 10 ^5.8 M _⊙ . The distance is measured using surface brightness fluctuations with both Legacy Surveys and deep Magellan/IMACS imaging data. Hedgehog is 1.7 Mpc from the nearest galaxy group, Centaurus A, and has no neighboring galaxies within 1 Mpc, making it one of the most isolated quiescent dwarf galaxies at this stellar mass. It has a red optical color and early-type morphology and shows no UV emission. This indicates that Hedgehog has an old stellar population and no ongoing star formation. Compared with other quiescent dwarfs in the Local Group and Local Volume, Hedgehog appears smaller in size for its luminosity but is consistent with the mass–size relations. Hedgehog might be a backsplash galaxy from the Centaurus A group, but it could also have been quenched in the field by ram pressure stripping in the cosmic web, reionization, or internal processes such as supernova and stellar feedback. Future observations are needed to fully unveil its formation, history, and quenching mechanisms.

The identification of red, apparently massive galaxies at z > 7 in early James Webb Space Telescope (JWST) photometry suggests a strongly accelerated time line compared to standard models of galaxy growth. A major uncertainty in the interpretation is whether the red colors are caused by evolved stellar populations, dust, or other effects such as emission lines or active galactic nuclei (AGNs). Here we show that three of the massive galaxy candidates at z = 6.7–8.4 have prominent Balmer breaks in JWST/NIRSpec spectroscopy from the RUBIES program. The Balmer breaks demonstrate unambiguously that stellar emission dominates at λ _rest = 0.4 μ m and require formation histories extending hundreds of millions of years into the past in galaxies only 600–800 Myr after the big bang. Two of the three galaxies also show broad Balmer lines, with H β FWHM > 2500 km s ^−1 , suggesting that dust-reddened AGNs contribute to, or even dominate, the spectral energy distributions of these galaxies at λ _rest ≳ 0.6 μ m. All three galaxies have relatively narrow [O iii ] lines, seemingly ruling out a high-mass interpretation if the lines arise in dynamically relaxed, inclined disks. Yet the inferred masses also remain highly uncertain. We model the high-quality spectra using Prospector to decompose the continuum into stellar and AGN components and explore limiting cases in stellar/AGN contribution. This produces a wide range of possible stellar masses, spanning M _⋆ ∼ 10 ^9 −10 ^11 M _⊙ . Nevertheless, all fits suggest a very early and rapid formation, most of which follow with a truncation in star formation. Potential origins and evolutionary tracks for these objects are discussed, from the cores of massive galaxies to low-mass galaxies with overmassive black holes. Intriguingly, we find all of these explanations to be incomplete; deeper and redder data are needed to understand the physics of these systems.

We present a measurement of the low-mass quiescent size–mass relation at cosmic noon (1 < z < 3) from the JWST PRIMER and UNCOVER treasury surveys, which highlights two distinct classes of quiescent galaxies. While the massive population is well studied at these redshifts, the low-mass end has been previously underexplored due to a lack of observing facilities with sufficient sensitivity and spatial resolution. We select a conservative sample of low-mass quiescent galaxy candidates using rest-frame UVJ colors and specific star formation rate criteria and measure galaxy morphology in both rest-frame UV/optical wavelengths (F150W) and rest-frame near-infrared (F444W). We confirm an unambiguous flattening of the low-mass quiescent size–mass relation, which results from the separation of the quiescent galaxy sample into two distinct populations at $\mathrm{log}({M}_{\star }/{M}_{\odot })\sim 10.3$ : low-mass quiescent galaxies that are notably younger and have disky structures, and massive galaxies consistent with spheroidal morphologies and older median stellar ages. These separate populations imply mass quenching dominates at the massive end while other mechanisms, such as environmental or feedback-driven quenching, form the low-mass end. This stellar mass-dependent slope of the quiescent size–mass relation could also indicate a shift from size growth due to star formation (low masses) to growth via mergers (massive galaxies). The transition mass between these two populations also corresponds with other dramatic changes and characteristic masses in several galaxy evolution scaling relations (e.g., star formation efficiency, dust obscuration, and stellar-to-halo mass ratios), further highlighting the stark dichotomy between low-mass and massive galaxy formation.

Active galactic nuclei (AGN) light curves observed with different wave bands show that the variability in longer wavelength bands lags the variability in shorter wavelength bands. Measuring these lags, or reverberation mapping, is used to measure the radial temperature profile and extent of AGN disks, typically with a reprocessing model that assumes X-rays are the main driver of the variability in other wavelength bands. To demonstrate how this reprocessing works with realistic accretion disk structures, we use 3D local shearing box multifrequency radiation magnetohydrodynamic simulations to model the UV-emitting region of an AGN disk, which is unstable to the magnetorotational instability and convection. At the same time, we inject hard X-rays (>1 keV) into the simulation box to study the effects of X-ray irradiation on the local properties of the turbulence and the resulting variability of the emitted UV light curve. We find that disk turbulence is sufficient to drive intrinsic variability in emitted UV light curves and that a damped random walk model is a good fit to this UV light curve for timescales >5 days. Meanwhile, X-ray irradiation has negligible impact on the power spectrum of the emitted UV light curve. Furthermore, the injected X-ray and emitted UV light curves are only correlated if there is X-ray variability on timescales >1 day, in which case we find a correlation coefficient r = 0.34. These results suggest that if the opacity for hard X-rays is scattering dominated as in the standard disk model, hard X-rays are not the main driver of reverberation signals.

Active galactic nuclei (AGN) are the signposts of black hole growth, and likely play an important role in galaxy evolution. An outstanding question is whether AGN of different spectral types indicate different evolutionary stages in the coevolution of black holes and galaxies. We present the angular correlation function between an AGN sample selected from Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) optical photometry and Wide-field Infrared Survey Explorer mid-IR photometry and a luminous red galaxy (LRG) sample from HSC-SSP. We investigate AGN clustering strength as a function of luminosity and spectral features across three independent HSC fields totaling ∼600 deg ^2 , for z ∈ 0.6 −1.2 and AGN with L _6 _ μ _m > 3 × 10 ^44 erg s ^−1 . There are ∼28,500 AGN and ∼1.5 million LRGs in our primary analysis. We determine the average halo mass for the full AGN sample ( M _h ≈ 10 ^12.9 h ^−1 M _⊙ ), and note that it does not evolve significantly as a function of redshift (over this narrow range) or luminosity. We find that, on average, unobscured AGN ( M _h ≈ 10 ^13.3 h ^−1 M _⊙ ) occupy ∼4.5× more massive halos than obscured AGN ( M _h ≈ 10 ^12.6 h ^−1 M _⊙ ), at 5 σ statistical significance using 1D uncertainties, and at 3 σ using the full covariance matrix, suggesting a physical difference between unobscured and obscured AGN, beyond the line-of-sight viewing angle. Furthermore, we find evidence for a halo mass dependence on reddening level within the Type I AGN population, which could support the existence of a dust-obscured phase. However, we also find that quite small systematic shifts in the redshift distributions of the AGN sample could explain current and previously observed differences in M _h .

The shallow potential wells of star-forming dwarf galaxies make their surrounding circumgalactic and intergalactic medium (CGM/IGM) sensitive laboratories for studying the inflows and outflows thought to regulate galaxy evolution. We present new absorption-line measurements in quasar sight lines, probing within projected distances of

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 2023 November, MegaScience obtained ∼30 arcmin ^2 of deep multiband NIRCam imaging centered on the z ∼ 0.3 A2744 cluster, including 11 medium-band filters and the two shortest-wavelength broadband filters, F070W and F090W. Together, MegaScience and the UNCOVER Cycle 1 treasury program provide a complete set of deep (∼28–30 mag _AB ) images in all NIRCam medium- and broadband filters. This unique data set 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 broadband and four medium-band filters from 0.9 to 4.8 μ m, expanding the footprint where robust spectral energy distribution (SED) fitting is possible. We provide example SEDs and multiband 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 [O iii ] 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 ( http://jwst-uncover.github.io/megascience ).

Poststarburst 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 Hubble Space Telescope (HST)/WFC3 F110W imaging to measure the sizes of 171 massive ( $\mathrm{log}({M}_{* }/{M}_{\odot })\sim \,11)$ spectroscopically identified PSBs at 1 < z 1.3 selected from the DESI Survey Validation luminous red galaxy sample. This statistical sample constitutes an order of magnitude increase from the ∼20 PSBs with space-based imaging and deep spectroscopy. We perform structural fitting of the target galaxies with pysersic and compare them to quiescent and star-forming galaxies in the 3D-HST survey. We find that these PSBs are more compact than the general population of quiescent galaxies, lying systematically ∼0.1 dex below the established size–mass relation. However, their central surface mass densities are similar to those of their quiescent counterparts ( $\,{\rm{log}}({{\rm{\Sigma }}}_{1{\rm{kpc}}}/({M}_{\odot }\,{{\rm{kpc}}}^{-2}))\sim 10.1$ ). These findings are easily reconciled by later ex situ growth via minor mergers or a slight progenitor bias. These PSBs are round in projection ( b / a _median ∼ 0.8), suggesting that they are primarily spheroids, not disks, in 3D. We find no correlation between the time since quenching and light-weighted PSB sizes or central densities. This disfavors apparent structural growth due to the fading of centralized starbursts in this galaxy population. Instead, we posit that the fast quenching of massive galaxies at this epoch occurs preferentially in galaxies with preexisting compact structures.

The James Webb Space Telescope (JWST) has uncovered a ubiquitous population of dust-obscured compact sources at z ≳ 4. Many of these objects exhibit signs of active galactic nucleus (AGN) activity, making their study crucial for understanding the formation of supermassive black holes (SMBHs) and their growth with host galaxies. In this work, we examine low and medium-resolution JWST/NIRSpec spectra from the JADES GTO public data release in the GOODS-N field of a red, luminous ( M _B ∼ −22.2 mag) and compact ( 4000 Å) continuum of this source is strongly dominated by a massive (log _10 [ M _* / M _⊙ ] ∼ 10.6), quenched (log _10 [sSFR/yr ^−1 ] < −11) galaxy, as indicated by the clear presence of a Balmer break and stellar absorption lines. Star formation history modeling reveals a starburst episode followed by rapid quenching about 200 Myr ago. The spectrum shows extremely broad (FWHM ∼2500 km s ^−1 ) H α emission and elevated optical line ratios, indicating an actively accreting SMBH. Moreover, our work has potentially revealed clear AGN signatures in the rest-UV in little red dots for the first time via the detection of a strong Ly α emission and a broad Mg ii doublet. The derived black hole mass of log _10 ( M _BH / M _⊙ ) ∼ 7.3 results in M _BH / M _* ∼ 0.04%, consistent with the local relations, unlike the elevated ratios in other high- z reddened AGN. Finally, we use JWST data from AGN at z = 4–10 to explore an evolutionary link between high- z reddened AGN, early quiescent galaxies, and local ellipticals.

Using medium-band imaging from the newly released Merian Survey, we conduct a nonparametric morphological analysis of H α emission maps and stellar continua for a sample of galaxies with $8\lesssim \mathrm{log}({M}_{\star }/{M}_{\odot })\lt 10.3$ at 0.064 < z < 0.1. We present a novel method for estimating the stellar continuum emission through the Merian Survey’s N708 medium-band filter, which we use to measure H α emission and produce H α maps for our sample of galaxies with seven-band Merian photometry and available spectroscopy. We measure nonparametric morphological statistics for the H α and stellar continuum images, explore how the morphology of the H α differs from the continuum, and investigate how the parameters evolve with the galaxies’ physical properties. In agreement with previous results for more massive galaxies, we find that the asymmetry of the stellar continuum increases with specific star formation rate (sSFR), and we extend the trend to lower masses, also showing that it holds for the asymmetry of the H α emission. We find that the lowest-mass galaxies with the highest sSFR have H α emission that is consistently heterogeneous and compact, while the less active galaxies in this mass range have H α emission that appears diffuse. At higher masses, our data do not span a sufficient range in sSFR to evaluate whether similar trends apply. We conclude that high sSFRs in low-mass galaxies likely result from dynamical instabilities that compress a galaxy’s molecular gas to a dense region near the center.

Quasar feedback is a key ingredient in shaping galaxy evolution. A rare population of extremely red quasars (ERQs) at z = 2−3 are often associated with high-velocity [O iii ] λ 5008 outflows and may represent sites of strong feedback. In this paper, we present an X-ray study of 50 ERQs to investigate the link between the X-ray and outflow properties of these intriguing objects. Using hardness ratio analysis, we confirm that the ERQs are heavily obscured systems with gas column density reaching N _H = 10 ^23−24 cm ^−2 . We identify 20 X-ray-nondetected ERQs at high mid-infrared (MIR) luminosities of ν L _ν _,6 _ μ _m ≳ 3 × 10 ^46 erg s ^−1 . By stacking the X-ray observations, we find that the nondetected ERQs are on average underluminous in X-rays by a factor of ∼10 for their MIR luminosities. We consider such X-ray weakness to be due to both heavy gas absorption and intrinsic factors. Moreover, we find that the X-ray-weak sources also display higher-velocity outflows. One option to explain this trend is that weaker X-rays facilitate more vigorous line-driven winds, which then accelerate the [O iii ]-emitting gas to kiloparsec scales. Alternatively, super-Eddington accretion could also lead to intrinsic X-ray weakness and more powerful continuum-driven outflow.

We report the spectroscopic confirmation of a massive ( $\mathrm{log}({M}_{\star }/{M}_{\odot })=10.34{\pm }_{0.07}^{0.06}$ ), Hubble Space Telescope–dark ( m _F150W − m _F444W = 3.6) quiescent galaxy at z _spec = 3.97 in the UNCOVER survey. NIRSpec/PRISM spectroscopy and a nondetection in deep Atacama Large Millimeter/submillimeter Array imaging surprisingly reveals that the galaxy is consistent with a low (

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 2022 November. The UNCOVER survey includes ultradeep (∼29–30AB) imaging of ∼45 arcmin ^2 on and around the well-studied A2744 galaxy cluster at z = 0.308 and will follow up ∼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 μ m 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, and 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 the full reduced mosaics of public JWST imaging including 45 arcmin ^2 NIRCam and 17 arcmin ^2 NIRISS mosaics on and around the A2744 cluster, including the Hubble Frontier Field primary and parallel footprints.

The supermassive black holes ( M _BH ∼ 10 ^6 –10 ^10 M _⊙ ) that power luminous active galactic nuclei (AGNs), i.e., quasars, generally show a correlation between thermal disk emission in the ultraviolet (UV) and coronal emission in hard X-rays. In contrast, some “massive” black holes (mBHs; M _BH ∼ 10 ^5 –10 ^6 M _⊙ ) in low-mass galaxies present curious X-ray properties with coronal radiative output up to 100× weaker than expected. To examine this issue, we present a pilot study incorporating Very Large Array radio observations of a sample of 18 high-accretion-rate (Eddington ratios L _bol / L _Edd > 0.1), mBH-powered AGNs ( M _BH ∼ 10 ^6 M _⊙ ) with Chandra X-ray coverage. Empirical correlations previously revealed in samples of radio-quiet, high-Eddington AGNs indicate that the radio–X-ray luminosity ratio, L _R / L _X , is approximately constant. Through multiwavelength analysis, we instead find that the X-ray-weaker mBHs in our sample tend toward larger values of L _R / L _X even though they remain radio-quiet per their optical–UV properties. This trend results in a tentative but highly intriguing correlation between L _R / L _X and X-ray weakness, which we argue is consistent with a scenario in which X-rays may be preferentially obscured from our line of sight by a “slim” accretion disk. We compare this observation to weak emission-line quasars (AGNs with exceptionally weak broad-line emission and a significant X-ray-weak fraction) and conclude by suggesting that our results may offer a new observational signature for finding high-accretion-rate AGNs.

We study the black hole mass–host galaxy stellar mass relation, M _BH – M _* , of a sample of z < 4 optically variable active galactic nuclei (AGNs) in the COSMOS field. The parent sample of 491 COSMOS AGNs were identified by optical variability from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) program. Using publicly available catalogs and spectra, we consolidate their spectroscopic redshifts and estimate virial black hole masses using broad-line widths and luminosities. We show that variability searches with deep, high-precision photometry like the HSC-SSP can identity AGNs in low-mass galaxies up to z ∼ 1. However, their black holes are more massive given their host galaxy stellar masses than predicted by the local relation for active galaxies. We report that z ∼ 0.5–4 variability-selected AGNs are meanwhile more consistent with the M _BH – M _* relation for local inactive early-type galaxies. This result is in agreement with most previous studies of the M _BH – M _* relation at similar redshifts and indicates that AGNs selected from variability are not intrinsically different from the broad-line Type 1 AGN population at similar luminosities. Our results demonstrate the need for robust black hole and stellar mass estimates for intermediate-mass black hole candidates in low-mass galaxies at similar redshifts to anchor this scaling relation. Assuming that these results do not reflect a selection bias, they appear to be consistent with self-regulated feedback models wherein the central black hole and stars in galaxies grow in tandem.

Observations with the James Webb Space Telescope (JWST) have uncovered numerous faint active galactic nuclei (AGN) at z ∼ 5 and beyond. These objects are key to our understanding of the formation of supermassive black holes (SMBHs), their coevolution with host galaxies, as well as the role of AGN in cosmic reionization. Using photometric colors and size measurements, we perform a search for compact red objects in an array of blank deep JWST/NIRCam fields totaling ∼640 arcmin ^2 . Our careful selection yields 260 reddened AGN candidates at 4 < z _phot < 9, dominated by a point-source-like central component (〈 r _eff 〉 < 130 pc) and displaying a dichotomy in their rest-frame colors (blue UV and red optical slopes). Quasar model fitting reveals our objects to be moderately dust-extincted ( A _V ∼ 1.6), which is reflected in their inferred bolometric luminosities of L _bol = 10 ^44–47 erg s ^−1 and fainter UV magnitudes M _UV ≃ −17 to −22. Thanks to the large areas explored, we extend the existing dusty AGN luminosity functions to both fainter and brighter magnitudes, estimating their number densities to be ×100 higher than for UV-selected quasars of similar magnitudes. At the same time, they constitute only a small fraction of all UV-selected galaxies at similar redshifts, but this percentage rises to ∼10% for M _UV ∼ − 22 at z ∼ 7. Finally, assuming a conservative case of accretion at the Eddington rate, we place a lower limit on the SMBH mass function at z ∼ 5, finding it to be consistent with both theory and previous JWST observations.

We present the final data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping (RM) project, a precursor to the SDSS-V Black Hole Mapper RM program. This data set includes 11 yr photometric and 7 yr spectroscopic light curves for 849 broad-line quasars over a redshift range of 0.1 < z < 4.5 and a luminosity range of L _bol = 10 ^44−47.5 erg s ^−1 , along with spectral and variability measurements. We report 23, 81, 125, and 110 RM lags (relative to optical continuum variability) for broad H α , H β , Mg ii , and C iv using the SDSS-RM sample, spanning much of the luminosity and redshift ranges of the sample. Using 30 low-redshift RM active galactic nuclei with dynamical-modeling black hole masses, we derive a new estimate of the average virial factor of $\left\langle \mathrm{log}f\right\rangle =0.62\pm 0.07$ for the line dispersion measured from the rms spectrum. The intrinsic scatter of individual virial factors is 0.31 ± 0.07 dex, indicating a factor of 2 systematic uncertainty in RM black hole masses. Our lag measurements reveal significant R – L relations for H β and Mg ii at high redshift, consistent with the latest measurements based on heterogeneous samples. While we are unable to robustly constrain the slope of the R – L relation for C iv given the limited dynamic range in luminosity, we found substantially larger scatter in C iv lags at fixed L _1350 . Using the SDSS-RM lag sample, we derive improved single-epoch (SE) mass recipes for H β , Mg ii , and C iv , which are consistent with their respective RM masses as well as between the SE recipes from two different lines, over the luminosity range probed by our sample. The new H β and Mg ii recipes are approximately unbiased estimators at given RM masses, but there are systematic biases in the C iv recipe. The intrinsic scatter of SE masses around RM masses is ∼0.45 dex for H β and Mg ii , increasing to ∼0.58 dex for C iv .

We report the discovery of large, ionized, [O ii ]-emitting circumgalactic nebulae around the majority of 30 UV-luminous quasars at z = 0.4–1.4 observed with deep, wide-field integral field spectroscopy with the Multi-Unit Spectroscopy Explorer (MUSE) by the Cosmic Ultraviolet Baryon Survey and MUSE Quasar Blind Emitters Survey. Among the 30 quasars, seven (23%) exhibit [O ii ]-emitting nebulae with major axis sizes greater than 100 kpc, 20 greater than 50 kpc (67%), and 27 (90%) greater than 20 kpc. Such large, optically emitting nebulae indicate that cool, dense, and metal-enriched circumgalactic gas is common in the halos of luminous quasars at intermediate redshift. Several of the largest nebulae exhibit morphologies that suggest interaction-related origins. We detect no correlation between the sizes and cosmological-dimming-corrected surface brightnesses of the nebulae and quasar redshift, luminosity, black hole mass, or radio-loudness, but find a tentative correlation between the nebulae and rest-frame [O ii ] equivalent width in the quasar spectra. This potential trend suggests a relationship between interstellar medium content and gas reservoirs on CGM scales. The [O ii ]-emitting nebulae around the z ≈ 1 quasars are smaller and less common than Ly α nebulae around z ≈ 3 quasars. These smaller sizes can be explained if the outer regions of the Ly α halos arise from scattering in more neutral gas, by evolution in the cool circumgalactic medium content of quasar-host halos, by lower-than-expected metallicities on ≳50 kpc scales around z ≈ 1 quasars, or by changes in quasar episodic lifetimes between z = 3 and 1.

We present the first results from the Revealing Low-Luminosity Active Galactic Nuclei (ReveaLLAGN) survey, a JWST survey of seven nearby LLAGNs. We focus on two observations with the Mid-Infrared Instrument (MIRI)’s Medium-Resolution Spectrometer of the nuclei of NGC 1052 and Sombrero (NGC 4594/M104). We also compare these data to public JWST data of higher-luminosity AGNs, NGC 7319 and NGC 7469. JWST clearly separates the AGN spectrum from the galaxy light even in Sombrero, the faintest target in our survey; the AGN components have very red spectra. We find that the emission-line widths in both NGC 1052 and Sombrero increase with increasing ionization potential, with FWHM > 1000 km s ^−1 for lines with ionization potential ≳ 50 eV. These lines are also significantly blueshifted in both LLAGNs. The high-ionization-potential lines in NGC 7319 show neither broad widths nor significant blueshifts. Many of the lower-ionization-potential emission lines in Sombrero show significant blue wings extending >1000 km s ^−1 . These features and the emission-line maps in both galaxies are consistent with outflows along the jet direction. Sombrero has the lowest-luminosity high-ionization-potential lines ([Ne v ] and [O iv ]) ever measured in the mid-infrared, but the relative strengths of these lines are consistent with higher-luminosity AGNs. On the other hand, the [Ne v ] emission is much weaker relative to the [Ne iii ] and [Ne ii ] lines of higher-luminosity AGNs. These initial results show the great promise that JWST holds for identifying and studying the physical nature of LLAGNs.

Drawing from the Chandra archive and using a carefully selected set of nearby dwarf galaxies, we present a calibrated high-mass X-ray binary (HMXB) luminosity function in the low-mass galaxy regime and search for an already hinted at dependence on metallicity. Our study introduces a new sample of local dwarf galaxies ( D < 12.5 Mpc and M _* < 5 × 10 ^9 M _⊙ ), expanding the specific star formation rates (sSFR) and gas-phase metallicities probed in previous investigations. Our analysis of the observed X-ray luminosity function indicates a shallower power-law slope for the dwarf galaxy HMXB population. In our study, we focus on dwarf galaxies that are more representative in terms of sSFR compared to prior work. In this regime, the HMXB luminosity function exhibits significant stochastic sampling at high luminosities. This likely accounts for the pronounced scatter observed in the galaxy-integrated HMXB population’s L _X /SFR versus metallicity for our galaxy sample. Our calibration is necessary to understand the active galactic nuclei content of low-mass galaxies identified in current and future X-ray survey fields and has implications for binary population synthesis models, as well as X-ray-driven cosmic heating in the early Universe.

We present the result of a spectroscopic campaign targeting active galactic nucleus (AGN) candidates selected using a novel unsupervised machine-learning (ML) algorithm trained on optical and mid-infrared photometry. AGN candidates are chosen without incorporating prior AGN selection criteria and are fainter, redder, and more numerous, ∼340 AGN deg ^−2 , than comparable photometric and spectroscopic samples. In this work, we obtain 178 rest-optical spectra from two candidate ML-identified AGN classes with the Hectospec spectrograph on the MMT Observatory. We find that our first ML-identified group is dominated by Type I AGNs (85%) with a

The James Webb Space Telescope is revealing a new population of dust-reddened broad-line active galactic nuclei (AGN) at redshifts z ≳ 5. Here we present deep NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (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 an 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 α with a FWHM > 2000 km s ^−1 , 20% of the 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 _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 _⊙ . While their UV luminosities (−16 > M _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 _⊙ black holes radiating at ∼10%–40% the Eddington limit. The number densities are surprisingly high at ∼10 ^−5 Mpc ^−3 mag ^−1 , 100 times more common than the faintest UV-selected quasars, while accounting for ∼1% of the UV-selected galaxies. While their UV faintness suggests they may not contribute strongly to reionization, their ubiquity poses challenges to models of black hole growth.

The era of the James Webb Space Telescope ushers stellar population models into uncharted territories, particularly at the high-redshift frontier. In a companion paper, we apply the Prospector Bayesian framework to jointly infer galaxy redshifts and stellar population properties from broadband photometry as part of the UNCOVER survey. Here we present a comprehensive error budget in spectral energy distribution (SED) modeling. Using a sample selected to have photometric redshifts higher than 9, we quantify the systematic shifts stemming from various model choices in inferred stellar mass, star formation rate (SFR), and age. These choices encompass different timescales for changes in the star formation history (SFH), nonuniversal stellar initial mass functions (IMF), and the inclusion of variable nebular abundances, gas density, and ionizing photon budget. We find that the IMF exerts the strongest influence on the inferred properties: the systematic uncertainties can be as much as 1 dex, 2–5 times larger than the formal reported uncertainties in mass and SFR, and importantly, exceed the scatter seen when using different SED fitting codes. Although the assumptions on the lower end of the IMF induce degeneracy, our findings suggest that a common practice in the literature of assessing uncertainties in SED-fitting processes by comparing multiple codes is substantively underestimating the true systematic uncertainty. Highly stochastic SFHs change the inferred SFH by much larger than the formal uncertainties, and introduce ∼0.8 dex systematics in SFR averaged over a short timescale and ∼0.3 dex systematics in average age. Finally, employing a flexible nebular emission model causes ∼0.2 dex systematic increase in mass and SFR, comparable to the formal uncertainty. This paper constitutes an initial step toward a complete uncertainty estimate in SED modeling.

It is exceedingly rare to find quiescent low-mass galaxies in the field at low redshift. UGC 5205 is an example of such a quenched field dwarf ( M _⋆ ∼ 3 × 10 ^8 M _⊙ ). Despite a wealth of cold gas ( M _HI ∼ 3.5 × 10 ^8 M _⊙ ) and UV emission that indicates significant star formation in the past few hundred megayears, there is no detection of H α emission—star formation in the last ∼10 Myr—across the face of the galaxy. Meanwhile, the near equal-mass companion of UGC 5205, PGC 027864, is starbursting (which has an H α equivalent width > 1000 Å). In this work, we present new Karl G. Jansky Very Large Array 21 cm line observations of UGC 5205, showing that the lack of star formation is caused by an absence of H i in the main body of the galaxy. The H i of UGC 5205 is highly disturbed; the bulk of the H i resides in several-kiloparsec–long tails, while the H i of PGC 027864 is dominated by ordered rotation. We model the stellar populations of UGC 5205 to show that, as indicated by the UV and H α emission, the galaxy underwent a coordinated quenching event ∼100–300 Myr ago. The asymmetry of outcomes for UGC 5205 and PGC 027864 demonstrate that major mergers can both quench and trigger star formation in dwarfs. However, because the gas remains bound to the system, we suggest that such mergers only temporarily quench star formation. We estimate a total quenched time of ∼560 Myr for UGC 5205, consistent with established upper limits on the quenched fraction of a few percent for dwarfs in the field.

We report JWST/NIRSpec spectra of three distant T-type brown dwarfs identified in the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) survey of the Abell 2744 lensing field. One source was previously reported as a candidate T dwarf on the basis of NIRCam photometry, while two sources were initially identified as candidate active galactic nuclei. Low-resolution 1–5 μ m spectra confirm the presence of molecular features consistent with T dwarf atmospheres, and comparison to spectral standards infers classifications of sdT1, T6, and T8–T9. The warmest source, UNCOVER-BD-1, shows evidence of subsolar metallicity, and atmosphere model fits indicate T _eff = 1300 K and [M/H] ∼ −1.0, making this one of the few spectroscopically confirmed T subdwarfs known. The coldest source, UNCOVER-BD-3, is near the T/Y dwarf boundary with T _eff = 550 K, and our analysis indicates the presence of PH _3 in the 3–5 μ m region, favored over CO _2 and a possible indicator of subsolar metallicity. We estimate distances of 0.9–4.5 kpc from the Galactic midplane, making these the most distant brown dwarfs with spectroscopic confirmation. Population simulations indicate high probabilities of membership in the Galactic thick disk for two of these brown dwarfs, and potential halo membership for UNCOVER-BD-1. Our simulations indicate that there are approximately 5 T dwarfs and 1–2 L dwarfs in the Abell 2744 field down to F444W = 30 AB mag, roughly one-third of which are thick disk members. These results highlight the utility of deep JWST/NIRSpec spectroscopy for identifying and characterizing the oldest metal-poor brown dwarfs in the Milky Way.

Quasar-driven galactic outflows are a major driver of the evolution of massive galaxies. We report observations of a powerful galactic-scale outflow in a z = 3 extremely red and intrinsically luminous ( L _bol ≃ 5 × 10 ^47 erg s ^−1 ) quasar SDSSJ1652 + 1728 with the Near-infrared Spectrograph on board JWST. We analyze the kinematics of rest-frame optical emission lines and identify the quasar-driven outflow extending out to ∼10 kpc from the quasar with a velocity offset of ( v _r = ± 500 km s ^−1 ) and high velocity dispersion (FWHM = 700–2400 km s ^−1 ). Due to JWST’s unprecedented surface brightness sensitivity in the near-infrared, we unambiguously show that the powerful high velocity outflow in an extremely red quasar encompasses a large swath of the host galaxy’s interstellar medium. Using the kinematics and dynamics of optical emission lines, we estimate the mass outflow rate—in the warm ionized phase alone—to be at least 2300 ± 1400 M _⊙ yr ^−1 . We measure a momentum flux ratio between the outflow and the quasar accretion disk of ∼1 on a kpc scale, indicating that the outflow was likely driven in a relatively high (>10 ^23 cm ^−2 ) column density environment through radiation pressure on dust grains. We find a coupling efficiency between the bolometric luminosity of the quasar and the outflow of 0.1%, matching the theoretical prediction of the minimum coupling efficiency necessary for negative quasar feedback. The outflow has sufficient energetics to drive the observed turbulence seen in shocked regions of the quasar host galaxy, which are likely directly responsible for prolonging the time that it takes for gas to cool efficiently.

Observations of high-redshift galaxies provide a critical direct test to the theories of early galaxy formation, yet to date, only three have been spectroscopically confirmed at z > 12. Due to strong gravitational lensing over a wide area, the galaxy cluster field A2744 is ideal for searching for the earliest galaxies. Here we present JWST/NIRSpec observations of two galaxies: a robust detection at ${z}_{\mathrm{spec}}={12.393}_{-0.001}^{+0.004}$ , and a plausible candidate at ${z}_{\mathrm{spec}}={13.079}_{-0.001}^{+0.013}$ . The galaxies are discovered in JWST/NIRCam imaging and their distances are inferred with JWST/NIRSpec spectroscopy, all from the JWST Cycle 1 UNCOVER Treasury survey. Detailed stellar population modeling using JWST NIRCam and NIRSpec data corroborates the primeval characteristics of these galaxies: low mass (∼10 ^8 M _⊙ ), young, rapidly assembling, metal-poor, and star-forming. Interestingly, both galaxies are spatially resolved, having lensing-corrected rest-UV effective radii on the order of 300–400 pc, which are notably larger than other spectroscopically confirmed systems at similar redshifts. The observed dynamic range of z ≳ 10 sizes spans over 1 order of magnitude, implying a significant scatter in the size–mass relation at early times. Deep into the epoch of reionization, these discoveries elucidate the emergence of the first galaxies.

Deep observations with the James Webb Space Telescope (JWST) have revealed an emerging population of red pointlike sources that could provide a link between the postulated supermassive black hole seeds and observed quasars. In this work, we present a JWST/NIRSpec spectrum from the JWST Cycle 1 UNCOVER Treasury survey of a massive accreting black hole at z = 8.50 displaying a clear broad-line component as inferred from the H β line with FWHM = 3439 ± 413 km s ^−1 , typical of the broad-line region of an active galactic nucleus (AGN). The AGN nature of this object is further supported by high ionization, as inferred from emission lines, and a point-source morphology. We compute a black hole mass of ${\mathrm{log}}_{10}({M}_{\mathrm{BH}}/{M}_{\odot })=8.17\pm 0.42$ and a bolometric luminosity of L _bol ∼ 6.6 × 10 ^45 erg s ^−1 . These values imply that our object is accreting at ∼40% of the Eddington limit. Detailed modeling of the spectral energy distribution in the optical and near-infrared, together with constraints from ALMA, indicate an upper limit on the stellar mass of ${\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })\lt 8.7$ , which would lead to an unprecedented ratio of black hole to host mass of at least ∼30%. This is orders of magnitude higher compared to the local QSOs but consistent with recent AGN studies at high redshift with JWST. This finding suggests that a nonnegligible fraction of supermassive black holes either started out from massive seeds and/or grew at a super-Eddington rate at high redshift. Given the predicted number densities of high- z faint AGN, future NIRSpec observations of larger samples will allow us to further investigate galaxy–black hole coevolution in the early Universe.

The James Webb Space Telescope is now detecting early black holes (BHs) as they transition from “seeds” to supermassive BHs. Recently, Bogdan et al. reported the detection of an X-ray luminous supermassive BH, UHZ-1, with a photometric redshift at z > 10. Such an extreme source at this very high redshift provides new insights on seeding and growth models for BHs given the short time available for formation and growth. Harnessing the exquisite sensitivity of JWST/NIRSpec, here we report the spectroscopic confirmation of UHZ-1 at z = 10.073 ± 0.002. We find that the NIRSpec/Prism spectrum is typical of recently discovered z ≈ 10 galaxies, characterized primarily by star formation features. We see no clear evidence of the powerful X-ray source in the rest-frame UV/optical spectrum, which may suggest heavy obscuration of the central BH, in line with the Compton-thick column density measured in the X-rays. We perform a stellar population fit simultaneously to the new NIRSpec spectroscopy and previously available photometry. The fit yields a stellar-mass estimate for the host galaxy that is significantly better constrained than prior photometric estimates ( ${M}_{\star }\sim {1.4}_{-0.4}^{+0.3}\times {10}^{8}$ M _⊙ ). Given the predicted BH mass ( M _BH ∼ 10 ^7 –10 ^8 M _⊙ ), the resulting ratio of M _BH / M _⋆ remains 2 to 3 orders of magnitude higher than local values, thus lending support to the heavy seeding channel for the formation of supermassive BHs within the first billion years of cosmic evolution.

This paper reports the first measurement of the relationship between turbulent velocity and cloud size in the diffuse circumgalactic medium (CGM) in typical galaxy halos at redshift z ≈ 0.4–1. Through spectrally resolved absorption profiles of a suite of ionic transitions paired with careful ionization analyses of individual components, cool clumps of size as small as l _cl ∼ 1 pc and density lower than n _H = 10 ^−3 cm ^−3 are identified in galaxy halos. In addition, comparing the line widths between different elements for kinematically matched components provides robust empirical constraints on the thermal temperature T and the nonthermal motions b _NT , independent of the ionization models. On average, b _NT is found to increase with l _cl following ${b}_{\mathrm{NT}}\propto {l}_{\mathrm{cl}}^{0.3}$ over three decades in spatial scale from l _cl ≈ 1 pc to l _cl ≈ 1 kpc. Attributing the observed b _NT to turbulent motions internal to the clumps, the best-fit b _NT – l _cl relation shows that the turbulence is consistent with Kolmogorov at

The [O iii ] 5007 Å emission line is the most common tracer of warm, ionized outflows in active galactic nuclei across cosmic time. JWST newly allows us to use mid-IR spectral features at both high spatial and spectral resolution to probe these same winds. Here we present a comparison of ground-based, seeing-limited [O iii ] and space-based, diffraction-limited [S iv ] 10.51 μ m maps of the powerful, kiloparsec-scale outflow in the Type 1 red quasar SDSS J110648.32+480712.3. The JWST data are from the Mid-InfraRed Instrument. There is a close match in resolution between the data sets (∼0.″6), in ionization potential of the O ^+2 and S ^+3 ions (35 eV) and in line sensitivity (1–2 × 10 ^−17 erg s ^−1 cm ^−2 arcsec ^−2 ). The [O iii ] and [S iv ] line shapes match in velocity and line width over much of the 20 kpc outflowing nebula, and [S iv ] is the brightest line in the rest-frame 3.5–19.5 μ m range, demonstrating its usefulness as a mid-IR probe of quasar outflows. [O iii ] is nevertheless intrinsically brighter and provides better contrast with the point-source continuum, which is strong in the mid-IR. There is a strong anticorrelation of [O iii ]/[S iv ] with average velocity, which is consistent with a scenario of differential obscuration between the approaching (blueshifted) and receding (redshifted) sides of the flow. The dust in the wind may also obscure the central quasar, consistent with models that attribute red quasar extinction to dusty winds.

In 2022 November, the James Webb Space Telescope (JWST) returned deep near-infrared images of A2744—a powerful lensing cluster capable of magnifying distant, incipient galaxies beyond it. Together with existing Hubble Space Telescope (HST) imaging, this publicly available data set 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 σ limiting magnitude of ∼30 mag in 0.″32 apertures. Photometry is performed using circular apertures on images matched to the point-spread function (PSF) of the reddest NIRCam broad band, F444W, and cleaned of bright cluster galaxies and the related intracluster light. To give an impression of the photometric performance, we measure photometric redshifts and achieve a σ _NMAD ≈ 0.03 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 of 2023.

We assemble a catalog of 15424 nearby galaxies within 50 Mpc with consistent and homogenized mass, distance, and morphological type measurements. Our catalog combines galaxies from HyperLeda, the NASA-Sloan Atlas, and the Catalog of Local Volume Galaxies. Distances for the galaxies combine best-estimates for flow-corrected redshift-based distances with redshift-independent distances. We also compile magnitude and color information for 11740 galaxies. We use the galaxy colors to estimate masses by creating self-consistent color—mass-to-light ratio relations in four bands; we also provide color transformations of all colors into Sloan g – i by using galaxies with overlapping color information. We compile morphology information for 13744 galaxies, and use the galaxy color information to separate early- and late-type galaxies. This catalog is widely applicable for studies of nearby galaxies and for placing these studies in the context of more distant galaxies. We present one application here: a preliminary analysis of the nuclear X-ray activity of galaxies. Out of 1506 galaxies within the sample that have available Chandra X-ray observations, we find that 291 have detected nuclear sources. Of the 291 existing Chandra detections, 249 have log( L _X ) > 38.3 and available stellar mass estimates. We find that the X-ray active fractions in early-type galaxies are higher than in late-type galaxies, especially for galaxy stellar masses between 10 ^9 and 10 ^10.5 M _⊙ . We show that these differences may be due at least in part to the increased astrometric uncertainties in late-type galaxies relative to early types.

The recent UNCOVER survey with the James Webb Space Telescope (JWST) exploits the nearby cluster A2744 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 ∼ 15. We show the redshift evolution of stellar ages, star formation rates, and rest-frame colors across the full range of 0.2 ≲ z ≲ 15. The galaxy properties are inferred using the Prospector Bayesian inference framework using informative Prospector - β priors on the masses and star formation histories to produce joint redshift and stellar populations posteriors. 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 σ _NMAD ∼ 0.03, of a similar quality to the established photometric redshift code EAzY . In line with the open-source scientific objective of this Treasury survey, we publicly release the stellar population catalog with this paper, derived from our photometric catalog adapting aperture sizes based on source profiles. This release (the catalog and all related documentation are accessible via the UNCOVER survey web page: https://jwst-uncover.github.io/DR2.html#SPSCatalogs with a copy deposited to Zenodo at doi: https://doi.org/10.5281/zenodo.8401181 ) 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.

We study the morphologies and structures of 57 dwarf galaxies that are representative of the general population of dwarf galaxies and compare their demographics to a sample of dwarf galaxies hosting optically selected active galactic nuclei (AGNs). The two samples span the same galaxy stellar mass (10 ^9 ≲ M _⋆ / M _⊙ ≲ 10 ^9.5 ) and color range, and the observations are well-matched in physical resolution. The fractions of irregular galaxies (14%) and early types/ellipticals (∼18%) are nearly identical among the two samples. However, among galaxies with disks (the majority of each sample), the AGN hosts almost always have a detectable (pseudo)bulge, while a large fraction of the non-AGN hosts are pure disk galaxies with no detectable (pseudo)bulge. Central point sources of light consistent with nuclear star clusters are detected in many of the non-AGN hosts. In contrast, central point sources detected in the AGN hosts are, on average, more than 2 orders of magnitude more luminous, suggesting the point sources in these objects are dominated by AGN light. The preference for (pseudo)bulges in dwarf AGN hosts may inform searches for massive black holes in dwarf galaxies and attempts to constrain the black hole occupation fraction, which, in turn, has implications for our understanding of black hole seeding mechanisms.

The variability of quasar light curves can be used to study the structure of quasar accretion disks. For example, continuum reverberation mapping uses delays between variability in short and long wavelength bands ( short lags) to measure the radial extent and temperature profile of the disk. Recently, a potential reverse lag, where variations in shorter wavelength bands lag the longer wavelength bands at the much longer viscous timescale, was detected for Fairall 9. Inspired by this detection, we derive a timescale for these long negative lags from fluctuation propagation models and recent simulations. We use this timescale to forecast our ability to detect long lags using the Vera Rubin Legacy Survey of Space and Time (LSST). After exploring several methods, including the interpolated cross-correlation function, a Von-Neumann estimator, javelin , and a maximum-likelihood Fourier method, we find that our two main methods, javelin and the maximum-likelihood method, can together detect long lags of up to several hundred days in mock LSST light curves. Our methods work best on proposed LSST cadences with long season lengths, but can also work for the current baseline LSST cadence, especially if we add observations from other optical telescopes during seasonal gaps. We find that LSST has the potential to detect dozens to hundreds of additional long lags. Detecting these long lags can teach us about the vertical structure of quasar disks and how it scales with different quasar properties.

Quantifying the connection between galaxies and their host dark matter halos has been key for testing cosmological models on various scales. Below M _⋆ ∼ 10 ^9 M _⊙ , such studies have primarily relied on the satellite galaxy population orbiting the Milky Way (MW). Here we present new constraints on the connection between satellite galaxies and their host dark matter subhalos using the largest sample of satellite galaxies in the Local Volume ( D ≲ 12 Mpc) to date. We use 250 confirmed and 71 candidate dwarf satellites around 27 MW-like hosts from the Exploration of Local VolumE Satellites (ELVES) Survey and use the semianalytical SatGen model for predicting the population of dark matter subhalos expected in the same volume. Through a Bayesian model comparison of the observed and the forward-modeled satellite stellar mass functions (SSMFs), we infer the satellite stellar-to-halo mass relation. We find that the observed SSMF is best reproduced when subhalos at the low-mass end are populated by a relation of the form ${M}_{\star }\propto {M}_{\mathrm{peak}}^{\alpha }$ , with a moderate slope of ${\alpha }_{\mathrm{const}}=2.10\pm 0.01$ and a low scatter, constant as a function of the peak halo mass, of ${\sigma }_{\mathrm{const}}={0.06}_{-0.05}^{+0.07}$ . A model with a steeper slope ( α _grow = 2.39 ± 0.06) and a scatter that grows with decreasing M _peak is also consistent with the observed SSMF but is not required. Our new model for the satellite–subhalo connection, based on hundreds of Local Volume satellite galaxies, is in line with what was previously derived using only MW satellites.

Massive galaxies formed most actively at redshifts z = 1–3 during the period known as “cosmic noon.” Here we present an emission-line study of the extremely red quasar SDSSJ165202.64+172852.3’s host galaxy at z = 2.94, based on observations with the Near Infrared Spectrograph integral field unit on board JWST. We use standard emission-line diagnostic ratios to map the sources of gas ionization across the host and a swarm of companion galaxies. The quasar dominates the photoionization, but we also discover shock-excited regions orthogonal to the ionization cone and the quasar-driven outflow. These shocks could be merger-induced or—more likely, given the presence of a powerful galactic-scale quasar outflow—these are signatures of wide-angle outflows that can reach parts of the galaxy that are not directly illuminated by the quasar. Finally, the kinematically narrow emission associated with the host galaxy presents as a collection of 1 kpc–scale clumps forming stars at a rate of at least 200 M _⊙ yr ^−1 . The interstellar medium within these clumps shows high electron densities, reaching up to 3000 cm ^−3 , with metallicities ranging from half to a third solar with a positive metallicity gradient, and V -band extinctions up to 3 mag. The star formation conditions are far more extreme in these regions than in local star-forming galaxies but consistent with those of massive galaxies at cosmic noon. The JWST observations simultaneously reveal an archetypal rapidly forming massive galaxy undergoing a merger, a clumpy starburst, an episode of obscured near-Eddington quasar activity, and an extremely powerful quasar outflow.

We study the broadband spectral energy distribution (SED) of the prototypical low-mass active galactic nucleus (AGN) in NGC 4395. We jointly model the optical through mid-IR SED with a combination of galaxy and AGN light, and find that on arcsecond scales the AGN dominates at most wavelengths. However, there is still some ambiguity about emission from the galaxy, owing partially to the strong short-term variability of the black hole. We investigate the use of smooth- and clumpy-torus models in order to disentangle the nuclear IR emission, as well as exploring the use of poloidal wind emission to account for the blue spectral slope observed in the near-IR. Even when simultaneously fitting the full optical–IR spectral range, we find that degeneracies still remain in the best-fit models. We conclude that high-spatial-resolution and wider-wavelength coverage with the JWST is needed to understand the mid-IR emission in this complex, highly variable object, which is the best nearby example to provide a blueprint to finding other low-mass AGNs via their mid-IR emission in the future.

We present a comprehensive multiwavelength study of five post-starburst galaxies with M _* > 10 ^11 M _⊙ at z ∼ 0.7, examining their stars, gas, and current and past star formation activities. Using optical images from the Subaru Telescope and Hubble Space Telescope, we observe a high incidence of companion galaxies and low surface brightness tidal features, indicating that quenching is closely related to interactions between galaxies. From optical spectra provided by the LEGA-C survey, we model the stellar continuum to derive the star formation histories and show the stellar masses of progenitors ranging from 2 × 10 ^9 M _⊙ to 10 ^11 M _⊙ , undergoing a burst of star formation several hundred million years prior to observation, with a decay timescale of ∼100 Myr. Our Atacama Large Millimeter/submillimeter Array observations detect CO(2-1) emission in four galaxies, with the molecular gas spreading over up to >1″, or ∼10 kpc, with a mass of up to ∼2 × 10 ^10 M _⊙ . However, star-forming regions are unresolved by either the slit spectra or 3 GHz continuum observed by the Very Large Array. Comparisons between the star formation rates (SFRs) and gas masses, and the sizes of CO emission and star-forming regions suggest a low star-forming efficiency. We show that the SFRs derived from IR and radio luminosities with commonly used calibrations tend to overestimate the true values because of the prodigious amount of radiation from old stars and the contribution from active galactic nuclei (AGNs), as the optical spectra reveal weak AGN-driven outflows.

Large diffuse galaxies are hard to find, but understanding the environments where they live, their numbers, and ultimately their origins, is of intense interest and importance for galaxy formation and evolution. Using Subaru’s Hyper Suprime-Cam Strategic Survey Program, we perform a systematic search for low surface brightness galaxies and present novel and effective methods for detecting and modeling them. As a case study, we surveyed 922 Milky Way analogs in the nearby Universe (0.01 < z < 0.04) and built a large sample of satellite galaxies that are outliers in the mass–size relation. These “ultra-puffy” galaxies (UPGs), defined to be 1.5 σ above the average mass–size relation, represent the tail of the satellite size distribution. We find that each MW analog hosts N _UPG = 0.31 ± 0.05 UPGs on average, which is consistent with but slightly lower than the observed abundance at this halo mass in the Local Volume. We also construct a sample of ultra-diffuse galaxies (UDGs) in MW analogs and find an abundance of N _UDG = 0.44 ± 0.05 per host. With literature results, we confirm that the UDG abundance scales with the host halo mass following a sublinear power law. We argue that our definition of UPGs, which is based on the mass–size relation, is more physically motivated than the common definition of UDGs, which depends on the surface brightness and size cuts and thus yields different surface mass density cuts for quenched and star-forming galaxies.

Recent observations have reignited interest in a population of dwarf galaxies that are large and diffuse for their mass, often called ultra-diffuse galaxies (UDGs). However, the origin and evolution of these mass–size outliers and the role of the environment are still unclear. Using the exquisitely deep and wide Hyper Suprime-Cam Strategic Survey images, we search for ultra-puffy galaxies (UPGs), defined as being 1.5 σ larger than the average size for their mass, around Milky Way–like galaxies. We present the sizes and radial distributions of mass–size outliers and derive their quenched fraction to explore the impact of the environment. Surprisingly, despite being outliers in size, the UPGs have a similar quenched fraction as normal-sized satellites of Milky Way analogs in both observations and simulations, suggesting that quenching is not tied to being a mass–size outlier. The quenched fraction is higher for the UPGs associated with redder hosts, as well as those that are closer to the host in projection. In contrast, the UDGs are overall redder and more quiescent compared with normal satellites. We show that the classic definition of UDGs is heavily weighted toward quenched galaxies and thus cannot be used for a study of quenching of mass–size outliers.

Globular clusters (GCs) provide valuable insight into the properties of their host galaxies’ dark matter halos. Using N -body simulations incorporating semianalytic dynamical friction and GC−GC merger prescriptions, we study the evolution of GC radial distributions and mass functions in cuspy and cored dark matter halos. Modeling the dynamics of the GC-rich system in the dwarf galaxy UGC 7369, we find that friction-induced inspiral and subsequent mergers of massive GCs can naturally and robustly explain the mass segregation of the GCs and the existence of a nuclear star cluster (NSC). However, the multiple mergers required to form the NSC only take place when the dark matter halo is cuspy. In a cored halo, stalling of the dynamical friction within the core halts the inspiral of the GCs, and so the GC merger rate falls significantly, precluding the formation of an NSC. We therefore argue that the presence of an NSC requires a cusp in UGC 7369. More generally, we propose that the presence of an NSC and the corresponding alteration of the GC mass function due to mergers may be used as an indicator of a cuspy halo for galaxies in which we expect NSC formation to be merger dominated. These observables represent a simple, powerful complement to other inner halo density profile constraint techniques and should allow for straightforward extension to larger samples.

We present Hubble Space Telescope photometry in the optical (F475X) and near-infrared (F110W) bands of the globular cluster (GC) systems of the inner halos of a sample of 15 massive elliptical galaxies. The targets are selected from the volume-limited MASSIVE survey, and chosen to sample a range of environments from sparsely populated groups to the brightest cluster galaxies in dense clusters. We also present a quantitative model of the relation between (F475X − F110W) color and cluster metallicity [M/H], using simulated GCs. Because much of the GC population in such galaxies is built up through accretion, the metallicity distribution of the GC systems might be expected to vary with galaxy environment. The photometry is used to create a completeness-corrected metallicity distribution for each galaxy in the sample, and to fit a double Gaussian curve to each histogram in order to model the two standard red and blue subpopulations. Finally, the properties of the GC metallicity distribution are correlated against galaxy environment. We find that almost no GCS properties and host galaxy environmental properties are correlated, with the exception of a weak but consistent correlation between blue fraction and n th-nearest-neighbor surface density. The results suggest that the systemic properties of the GC systems, at least in the inner to midhalo regions, are influenced more strongly by the local environment at early times, rather than by the environmental properties we see today.

Quasar feedback may regulate the growth of supermassive black holes, quench coeval star formation, and impact galaxy morphology and the circumgalactic medium. However, direct evidence for quasar feedback in action at the epoch of peak black hole accretion at z ≈ 2 remains elusive. A good case in point is the z = 1.6 quasar WISEA J100211.29+013706.7 (XID 2028), where past analyses of the same ground-based data have come to different conclusions. Here, we revisit this object with the integral-field unit of the Near Infrared Spectrograph on board the JWST as part of Early Release Science program Q3D. The excellent angular resolution and sensitivity of the JWST data reveal new morphological and kinematic substructures in the outflowing gas plume. An analysis of the emission-line ratios indicates that photoionization by the central quasar dominates the ionization state of the gas with no obvious sign for a major contribution from hot young stars anywhere in the host galaxy. The rest-frame near-UV emission aligned along the wide-angle cone of outflowing gas is interpreted as a scattering cone. The outflow has cleared a channel in the dusty host galaxy, through which some of the quasar ionizing radiation is able to escape and heat the surrounding interstellar and circumgalactic media. Although the warm ionized outflow is not powerful enough to impact the host galaxy via mechanical feedback, radiative feedback by the active galactic nucleus, aided by the outflow, may help to explain the unusually small molecular gas mass fraction in the galaxy host.

We report the detection of a long-timescale negative lag, where the blue bands lag the red bands, in the nearby Seyfert 1 galaxy Fairall 9, with two independent methods. Active Galactic Nuclei (AGNs) light curves show variability over a wide range of timescales. By measuring time lags between different wavelengths, the otherwise inaccessible structure and kinematics of the accretion disk can be studied. One common approach, reverberation mapping, quantifies the continuum and line lags moving outward through the disk at the light-travel time, revealing the size and temperature profile of the disk. Inspired by numerical simulations, we expect longer lags to exist in AGN light curves that travel inward on longer timescales, tracing the accretion process itself. By analyzing AGN light curves in both temporal and frequency space, we report the detection of long-timescale lags (∼−70 days) in Fairall 9 that propagate in the opposite direction to the reverberation lag. The short continuum lag (

Recent JWST/NIRCam imaging taken for the ultra-deep UNCOVER program reveals a very red dropout object at z _phot ≃ 7.6, triply imaged by the galaxy cluster A2744 ( z _d = 0.308). All three images are very compact, i.e., unresolved, with a delensed size upper limit of r _e ≲ 35 pc. The images have apparent magnitudes of m _F444W ∼ 25−26 AB, and the magnification-corrected absolute UV magnitude of the source is M _UV,1450 = −16.81 ± 0.09. From the sum of observed fluxes and from a spectral energy distribution (SED) analysis, we obtain estimates of the bolometric luminosities of the source of L _bol ≳ 10 ^43 erg s ^−1 and L _bol ∼ 10 ^44 –10 ^46 erg s ^−1 , respectively. Based on its compact, point-like appearance, its position in color–color space, and the SED analysis, we tentatively conclude that this object is a UV-faint dust-obscured quasar-like object, i.e., an active galactic nucleus at high redshift. We also discuss other alternative origins for the object’s emission features, including a massive star cluster, Population III, supermassive, or dark stars, or a direct-collapse black hole. Although populations of red galaxies at similar photometric redshifts have been detected with JWST, this object is unique in that its high-redshift nature is corroborated geometrically by lensing, that it is unresolved despite being magnified—and thus intrinsically even more compact—and that it occupies notably distinct regions in both size–luminosity and color–color space. Planned UNCOVER JWST/NIRSpec observations, scheduled in Cycle 1, will enable a more detailed analysis of this object.

Isolated dwarf galaxies usually exhibit robust star formation but satellite dwarf galaxies are often devoid of young stars, even in Milky Way–mass groups. Dwarf galaxies thus offer an important laboratory of the environmental processes that cease star formation. We explore the balance of quiescent and star-forming galaxies (quenched fractions) for a sample of ∼400 satellite galaxies around 30 Local Volume hosts from the Exploration of Local VolumE Satellites (ELVES) Survey. We present quenched fractions as a function of satellite stellar mass, projected radius, and host halo mass, to conclude that overall, the quenched fractions are similar to the Milky Way, dropping below 50% at satellite M _* ≈ 10 ^8 M _⊙ . We may see hints that quenching is less efficient at larger radii. Through comparison with the semianalytic modeling code SatGen , we are also able to infer average quenching times as a function of satellite mass in host halo-mass bins. There is a gradual increase in quenching time with satellite stellar mass rather than the abrupt change from rapid to slow quenching that has been inferred for the Milky Way. We also generally infer longer average quenching times than recent hydrodynamical simulations. Our results are consistent with models that suggest a wide range of quenching times are possible via ram pressure stripping, depending on the clumpiness of the circumgalactic medium, the orbits of the satellites, and the degree of earlier preprocessing.

We present visual classifications of merger-induced tidal disturbances in 143 M _* ∼ 10 ^11 M _⊙ post-starburst galaxies at z ∼ 0.7 identified in the $\mathrm{SQuIGG}\vec{L}{\rm{E}}$ Sample. This sample spectroscopically selects galaxies from the Sloan Digital Sky Survey that have stopped their primary epoch of star formation within the past ∼500 Myr. Visual classifications are performed on Hyper Suprime-Cam 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 ${3.6}_{-1.3}^{+2.9}$ times the disturbance rate of older quiescent galaxies and ${2.1}_{-.73}^{+1.9}$ times the disturbance rate of star-forming galaxies. Assuming tidal features persist for ≲500 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 10 young (≲150 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.