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Massive galaxy-scale outflows of gas are one of the most commonly-invokedmechanisms to regulate the growth and evolution of galaxies throughout theuniverse. While the gas in outflows spans a large range of temperatures anddensities, the cold molecular phase is of particular interest because molecularoutflows may be capable of suppressing star formation in galaxies by removingthe star-forming gas. We have conducted the first survey of molecular outflowsat z > 4, targeting 11 strongly-lensed dusty, star-forming galaxies (DSFGs)with high-resolution Atacama Large Millimeter Array (ALMA) observations of OH119um absorption as an outflow tracer. In this first paper, we give an overviewof the survey, focusing on the detection rate and structure of molecularoutflows. We find unambiguous evidence for outflows in 8/11 (73%) galaxies,more than tripling the number known at z > 4. This implies that molecular windsin z > 4 DSFGs must have both a near-unity occurrence rate and large openingangles to be detectable in absorption. Lensing reconstructions reveal that500pc-scale clumpy structures in the outflows are common. The individual clumpsare not directly resolved, but from optical depth arguments we expect thatfuture observations will require 50-200pc spatial resolution to do so. We donot detect high-velocity [CII] wings in any of the sources with clear OHoutflows, indicating that [CII] is not a reliable tracer of molecular outflows.Our results represent a first step toward characterizing molecular outflows atz > 4 at the population level, demonstrating that large-scale outflows areubiquitous among early massive, dusty galaxies.

Galactic outflows of molecular gas are a common occurrence in galaxies andmay represent a mechanism by which galaxies self-regulate their growth,redistributing gas that could otherwise have formed stars. We previouslypresented the first survey of molecular outflows at z > 4 towards a sample ofmassive, dusty galaxies. Here we characterize the physical properties of themolecular outflows discovered in our survey. Using low-redshift outflows as atraining set, we find agreement at the factor-of-two level between severaloutflow rate estimates. We find molecular outflow rates 150-800Msun/yr andinfer mass loading factors just below unity. Among the high-redshift sources,the molecular mass loading factor shows no strong correlations with any othermeasured quantity. The outflow energetics are consistent with expectations formomentum-driven winds with star formation as the driving source, with no needfor energy-conserving phases. There is no evidence for AGN activity in oursample, and while we cannot rule out deeply-buried AGN, their presence is notrequired to explain the outflow energetics, in contrast to nearby obscuredgalaxies with fast outflows. The fraction of the outflowing gas that willescape into the circumgalactic medium (CGM), though highly uncertain, may be ashigh as 50%. This nevertheless constitutes only a small fraction of the totalcool CGM mass based on a comparison to z~2-3 quasar absorption line studies,but could represent >~10% of the CGM metal mass. Our survey offers the firststatistical characterization of molecular outflow properties in the very earlyuniverse.

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 ).

Using integrated spectra for two gravitationally lensed galaxies from the JWST TEMPLATES Early Release Science program, we analyze faint auroral lines, which provide direct measurements of the gas-phase chemical abundance. For the brighter galaxy, SGAS1723+34 ( z = 1.3293), we detect the [O iii ] λ 4363, [S iii ] λ 6312, and [O ii ] λ λ 7320, 7330 auroral emission lines, and set an upper limit for the [N ii ] λ 5755 line. For the second galaxy, SGAS1226+21 ( z = 2.925), we do not detect any auroral lines, and report upper limits. With these measurements and upper limits, we constrain the electron temperatures in different ionization zones within both of these galaxies. For SGAS1723+34, where auroral lines are detected, we calculate direct oxygen and nitrogen abundances, finding an N/O ratio consistent with observations of nearby ( z ∼ 0) galaxies. These observations highlight the potent combination of JWST and gravitational lensing to measure faint emission lines in individual distant galaxies and to directly study the chemical abundance patterns in those galaxies.

We present the first spatially resolved maps of gas-phase metallicity for two dust-obscured star-forming galaxies at z ∼ 4, from the JWST TEMPLATES Early Release Science program, derived from NIRSpec integral field unit spectroscopy of the H α and [N ii ] emission lines. Empirical optical line calibrations are used to determine that the sources are globally enriched to near-solar levels. While one source shows elevated [N ii ]/H α ratios and broad H α emission consistent with the presence of an active galactic nucleus in a ≳1 kpc region, we argue that both systems have already undergone significant metal enrichment as a result of their extremely high star formation rates. Utilizing Atacama Large Millimeter/submillimeter Array rest-frame 380 μ m continuum and [C i ]( ^3 P _2 – ^3 P _1 ) line maps we compare the spatial variation of the metallicity and gas-to-dust ratio in the two galaxies, finding the two properties to be anticorrelated on highly resolved spatial scales, consistent with various literature studies of z ∼ 0 galaxies. The data are indicative of the enormous potential of JWST to probe the enrichment of the interstellar medium on ∼kpc scales in extremely dust-obscured systems at z ∼ 4 and beyond.

We present a sample of 30 massive (log( M _* / M _⊙ ) > 11) z = 3–5 quiescent galaxies selected from the Spitzer-HETDEX Exploratory Large Area (SHELA) Survey and observed at 1.1 mm with Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 observations. These ALMA observations would detect even modest levels of dust-obscured star formation, on the order of ∼20 M _⊙ yr ^−1 at z ∼ 4 at the 1 σ level, allowing us to quantify the amount of contamination from dusty star-forming sources in our quiescent sample. Starting with a parent sample of candidate massive quiescent galaxies from the Stevans et al. v1 SHELA catalog, we use the Bayesian B agpipes spectral energy distribution fitting code to derive robust stellar masses ( M _* ) and star formation rates (SFRs) for these sources, and select a conservative sample of 36 candidate massive ( M _* > 10 ^11 M _⊙ ) quiescent galaxies, with specific SFRs >2 σ below the Salmon et al. star-forming main sequence at z ∼ 4. Based on the ALMA imaging, six of these candidate quiescent galaxies show the presence of significant dust-obscured star formation, and thus were removed from our final sample. This implies a ∼17% contamination rate from dusty star-forming galaxies with our selection criteria using the v1 SHELA catalog. This conservatively selected quiescent galaxy sample at z = 3–5 will provide excellent targets for future observations to constrain better how massive galaxies can both grow and shut down their star formation in a relatively short period.

SPT0311-58, a system of two interacting galaxies in the Epoch of Reionization, exists in one of the rarest, most massive dark matter halos theoretically possible in that era. Studying the interstellar medium (ISM) in these galaxies can illuminate the process of galaxy formation in the early Universe. In this work, we explore the multiphase ISM in this system, using ALMA observations of the [C ii ] 158, [O i ] 146, [N ii ] 122, and [O iii ] 88 fine-structure lines and dust continuum. We find wide variations in line ratios between the eastern and western galaxies, as well as across the western galaxy. Continuum colors indicate that SPT0311-58 E has a higher ionization parameter ( $\mathrm{log}U\approx -2.8$ ) than SPT0311-58 W ( $\mathrm{log}U\approx -3.1$ ). The ratio of [O iii ] 88–[N ii ] 122 and the ionization parameter constraints combine to demonstrate near-solar metallicity in these objects just 800 Myr after the Big Bang.

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.

REQUIEM-2D (Resolving Quiescent Magnified Galaxies with 2D Grism Spectroscopy) comprises a sample of eight massive ( ${\rm{log}}({M}_{\ast }/{M}_{\odot })\gt 10.6$ ) strongly lensed quiescent galaxies at z ∼ 2. REQUIEM-2D combines the natural magnification from strong gravitational lensing with the high-spatial-resolution grism spectroscopy of the Hubble Space Telescope through a spectrophotometric fit to study spatially resolved stellar populations. We show that quiescent galaxies in the REQUIEM-2D survey have diverse formation histories with age gradients at the 1 σ –3 σ level, including examples of (1) a younger central region supporting outside-in formation, (2) flat age gradients that show evidence for both spatially uniform early formation and inside-out quenching, and (3) regions at a fixed radial distance having different ages (such asymmetries cannot be recovered when averaging stellar population measurements azimuthally). The typical dust attenuation curve for the REQUIEM-2D galaxies is constrained to be steeper than Calzetti’s law in the UV and generally consistent with A _V < 1. Combined together and accounting for the different physical radial distances and formation timescales, we find that the REQUIEM-2D galaxies that formed earlier in the universe exhibit slow and uniform growth in their inner core, whereas the galaxies that formed later have rapid inner growth in their inner core with younger ages than the outskirts. These results challenge the currently accepted paradigm of how massive quiescent galaxies form, where the earliest galaxies are thought to form most rapidly. Significantly larger samples close to the epoch of formation with similar data quality and higher spectral resolution are required to validate this finding.