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Recent zoom-in cosmological simulations have shown that stellar feedback can flatten the inner density profile of the dark matter halo in low-mass galaxies. A correlation between the stellar/gas velocity dispersion (σ star, σ gas) and the specific star formation rate (sSFR) is predicted as an observational test of the role of stellar feedback in re-shaping the dark matter density profile. In this work we test the validity of this prediction by studying a sample of star-forming galaxies at 0.6 < z < 1.0 from the LEGA-C survey, which provides high signal-to-noise measurements of stellar and gas kinematics. We find that a weak but significant correlation between σ star (and σ gas) and sSFR indeed exists for galaxies in the lowest mass bin (M ∗ ∼ 1010 M o˙). This correlation, albeit with a ∼35% scatter, holds for different tracers of star formation, and becomes stronger with redshift. This result generally agrees with the picture that at higher redshifts star formation rate was generally higher, and galaxies at M ∗ ≲ 1010 M o˙ have not yet settled into a disk. As a consequence, they have shallower gravitational potentials more easily perturbed by stellar feedback. The observed correlation between σ star (and σ gas) and sSFR supports the scenario predicted by cosmological simulations, in which feedback-driven outflows cause fluctuations in the gravitation potential that flatten the density profiles of low-mass galaxies.

We present ionized gas kinematics for 681 galaxies at z &tild; 1.4-3.8 from the MOSFIRE Deep Evolution Field survey, measured using models that account for random galaxy-slit misalignments together with structural parameters derived from CANDELS Hubble Space Telescope (HST) imaging. Kinematics and sizes are used to derive dynamical masses. Baryonic masses are estimated from stellar masses and inferred gas masses from dust-corrected star formation rates (SFRs) and the Kennicutt-Schmidt relation. We measure resolved rotation for 105 galaxies. For the remaining 576 galaxies we use models based on HST imaging structural parameters together with integrated velocity dispersions and baryonic masses to statistically constrain the median ratio of intrinsic ordered to disordered motion,. We find that increases with increasing stellar mass and decreasing specific SFR (sSFR). These trends may reflect marginal disk stability, where systems with higher gas fractions have thicker disks. For galaxies with detected rotation we assess trends between their kinematics and mass, sSFR, and baryon surface density (Σbar,e). Intrinsic dispersion correlates most with Σbar,e, and velocity correlates most with mass. By comparing dynamical and baryonic masses, we find that galaxies at z &tild; 1.4-3.8 are baryon dominated within their effective radii (RE), with Mdyn/Mbaryon increasing over time. The inferred baryon fractions within RE, fbar, decrease over time, even at fixed mass, size, or surface density. At fixed redshift, fbar does not appear to vary with stellar mass but increases with decreasing RE and increasing Σbar,e. For galaxies at z ≥ 2, the median inferred baryon fractions generally exceed 100%. We discuss possible explanations and future avenues to resolve this tension.

We constrain gas inflow speeds in star-forming galaxies with color gradients consistent with inside-out disk growth. Our method combines new measurements of disk orientation with previously described circumgalactic absorption in background quasar spectra. Two quantities, a position angle and an axis ratio, describe the projected shape of each galactic disk on the sky, leaving an ambiguity about which side of the minor axis is tipped toward the observer. This degeneracy regarding the 3D orientation of disks has compromised previous efforts to measure gas inflow speeds. We present Hubble Space Telescope and Keck/LGSAO imaging that resolves the spiral structure in five galaxies at redshift z ≈ 0.2. We determine the sign of the disk inclination for four galaxies, under the assumption that spiral arms trail the rotation. We project models for both radial infall in the disk plane and circular orbits onto each quasar sightline. We compare the resulting line-of-sight velocities to the observed velocity range of Mg ii absorption in spectra of background quasars, which intersect the disk plane at radii between 69 and 115 kpc. For two sightlines, we constrain the maximum radial inflow speeds as 30-40 km s-1. We also rule out a velocity component from radial inflow in one sightline, suggesting that the structures feeding gas to these growing disks do not have unity covering factor. We recommend appropriate selection criteria for building larger samples of galaxy-quasar pairs that produce orientations sensitive to constraining inflow properties.

We present measurements of [S III]λλ9069,9531 for a sample of z ∼ 1.5 star-forming galaxies, the first representative sample with measurements of these lines at z ≿ 0.1. We employ the line ratio S32 ≡ [S III]λλ9069,9531/[S II]λλ6716,6731 as a novel probe of evolving interstellar medium (ISM) conditions. Since this ratio includes the low-ionization line [S II], it is crucial that the effects of diffuse ionized gas (DIG) on emission-line ratios be accounted for in z ∼ 0 galaxy spectra, or else that comparisons be made to samples of local H II regions in which DIG emission is not present. We find that S32 decreases with increasing stellar mass at both z ∼ 1.5 and z ∼ 0, but with a shallow slope suggesting S32 has a weak dependence on metallicity, in contrast with [O III]/[O II] that displays a strong metallicity dependence. As a result, S32 only mildly evolves with redshift at fixed stellar mass. The z ∼ 1.5 sample is systematically offset toward lower S32 and higher [S II]/Hα at fixed [O III]/Hβ relative to z = 0 H II regions. We find that such trends can be explained by a scenario in which the ionizing spectrum is harder at fixed O/H with increasing redshift, but are inconsistent with an increase in ionization parameter at fixed O/H. This analysis demonstrates the advantages of expanding beyond the strongest rest-optical lines for evolutionary studies, and the particular utility of [S III] for characterizing evolving ISM conditions and stellar compositions. These measurements provide a basis for estimating [S III] line strengths for high-redshift galaxies, a line that the James Webb Space Telescope will measure out to z ∼ 5.5.

We present measurements of [S III]λλ9069,9531 for a sample of z ∼ 1.5 star-forming galaxies, the first representative sample with measurements of these lines at z ≿ 0.1. We employ the line ratio S32 ≡ [S III]λλ9069,9531/[S II]λλ6716,6731 as a novel probe of evolving interstellar medium (ISM) conditions. Since this ratio includes the low-ionization line [S II], it is crucial that the effects of diffuse ionized gas (DIG) on emission-line ratios be accounted for in z ∼ 0 galaxy spectra, or else that comparisons be made to samples of local H II regions in which DIG emission is not present. We find that S32 decreases with increasing stellar mass at both z ∼ 1.5 and z ∼ 0, but with a shallow slope suggesting S32 has a weak dependence on metallicity, in contrast with [O III]/[O II] that displays a strong metallicity dependence. As a result, S32 only mildly evolves with redshift at fixed stellar mass. The z ∼ 1.5 sample is systematically offset toward lower S32 and higher [S II]/Hα at fixed [O III]/Hβ relative to z = 0 H II regions. We find that such trends can be explained by a scenario in which the ionizing spectrum is harder at fixed O/H with increasing redshift, but are inconsistent with an increase in ionization parameter at fixed O/H. This analysis demonstrates the advantages of expanding beyond the strongest rest-optical lines for evolutionary studies, and the particular utility of [S III] for characterizing evolving ISM conditions and stellar compositions. These measurements provide a basis for estimating [S III] line strengths for high-redshift galaxies, a line that the James Webb Space Telescope will measure out to z ∼ 5.5.

Jellyfish galaxies are starburst galaxies with ram-pressure-stripped tails and blue star-forming knots. These galaxies show a snapshot of star formation enhancement triggered by ram pressure stripping (RPS), being important targets for studying the RPS-induced star formation in gas-rich galaxies. Here we investigate the star formation activity of five jellyfish galaxies in massive clusters, using Gemini GMOS/IFU observations. From the H α -derived star formation rates (SFRs), we find that our sample shows higher SFR excess to the star formation main sequence than the jellyfish galaxies in low-mass clusters. From the compiled sample of jellyfish galaxies in low-mass to high-mass host clusters, we suggest that the star formation activity of jellyfish galaxies has positive correlations with host cluster mass and degree of RPS. These relationships imply that higher ram pressure environments tend to trigger stronger starbursts in jellyfish galaxies in the early stage of RPS. [ABSTRACT FROM AUTHOR]

Integral field spectroscopic studies of galaxies in dense environments, such as clusters and groups of galaxies, have provided new insights for understanding how star formation proceeds, and quenches. I present the spatially resolved view of the star formation activity and its link with the multiphase gas in cluster galaxies based on MUSE and multi-wavelength data of the GASP survey. I discuss the link among the different scales (i.e. the link between the spatially resolved and the global star formation rate-stellar mass relation), the spatially resolved signatures and the quenching histories of jellyfish (progenitors) and post-starburst (descendants) galaxies in clusters. Finally, I discuss the multi-wavelength view of star-forming clumps both in galaxy disks and in the tails of stripped gas. [ABSTRACT FROM AUTHOR]

At least half of the local galaxies reside in galaxy groups, which indicates that the group is the common environment where galaxies evolve. Therefore, it is important to probe how significantly galaxies are affected by group environmental processes, in order to obtain a better understanding of galaxy evolution. We carried out a new CO imaging survey for 31 galaxies in the IC 1459 and NGC 4636 groups, using the Atacama Compact Array, to study the effect of the group environment on the molecular gas properties and the star formation activity. With our resolved CO data, combined with high-resolution H i images, we find asymmetric CO and H i distributions in the group galaxies. Compared to isolated galaxies, group members have relatively low molecular gas fraction and low star formation rate. These results suggest that the group environment can change the properties of cold gas components and star formation in group galaxies. [ABSTRACT FROM AUTHOR]

Green valley galaxies (by selection) exhibit lower specific star formation rates and are thought to be in the transition from the active star-forming phase to the quiescent state. Physical mechanisms responsible for the depleted star formation in green valley galaxies, however, are still under debate. Using the ALMA-MaNGA Quenching and STar formation (ALMaQUEST) CO observations, we study the so-called 'resolved star formation scaling relations', which describe relationships among surface densities of star formation rate, stellar mass, and molecular gas mass. By comparing the kpc-scale scaling relations between the main sequence and green valley galaxies, we are able to quantify if the deficit of star formation in green valley galaxies is driven by depleted molecular gas or inefficient star formation. And finally, we present our recent ALMA dense gas (HCN and HCO+) observations for a set of selected ALMaQUEST galaxies to discuss whether the green valley galaxies lack dense molecular gas or not. [ABSTRACT FROM AUTHOR]

We present a first sample of 117 [O iii ] λλ 4960, 5008–selected star-forming galaxies at 5.33 < z < 6.93 detected in JWST/NIRCam 3.5 μ m slitless spectroscopy of a 6.′ 5 × 3.′ 4 field centered on the hyperluminous quasar SDSS J0100+2802, obtained as part of the Emission-line galaxies and Intergalactic Gas in the Epoch of Reionization (EIGER) survey. Three prominent galaxy overdensities are observed, one of them at the redshift of the quasar. Galaxies are found within 200 pkpc and 105 km s−1 of four known metal absorption-line systems. We focus on the role of the galaxies in ionizing the intergalactic medium (IGM) during the later stages of cosmic reionization and construct the mean Ly α and Ly β transmission as a function of distance from the galaxies. At the lowest redshifts in our study, 5.3 < z < 5.7, the IGM transmission rises monotonically with distance from the galaxies, as seen previously at lower redshifts. In contrast, at 5.7 < z < 6.14, the transmission of both Ly α and Ly β first increases with distance but then peaks at a distance of 5 cMpc before declining. Finally, in the region 6.15 < z < 6.26, where the additional ionizing radiation from the quasar dominates, the monotonic increase in transmission with distance is reestablished. This result is interpreted to represent evidence that the transmission of the IGM at z ∼ 5.9 toward J0100+2802 results from the "local" ionizing radiation of galaxies that dominates over the much-reduced cosmic background. [ABSTRACT FROM AUTHOR]

We report the discovery of five bright, strong gravitationally lensed galaxies at 3 < z < 4: COOL J0101+2055 (z = 3.459), COOL J0104−0757 (z = 3.480), COOL J0145+1018 (z = 3.310), COOL J0516−2208 (z = 3.549), and COOL J1356+0339 (z = 3.753). These galaxies have magnitudes of r AB, z AB < 21.81 mag and are lensed by galaxy clusters at 0.26 < z < 1. This sample nearly doubles the number of known bright lensed galaxies with extended arcs at 3 < z < 4. We characterize the lensed galaxies using ground-based grz / giy imaging and optical spectroscopy. We report model-based magnitudes and derive stellar masses, dust content, and star formation rates via stellar population synthesis modeling. Building lens models based on ground-based imaging, we estimate source magnifications ranging from ∼29 to ∼180. Combining these analyses, we derive demagnified stellar masses in the range log 10 (M * / M ⊙) ∼ 9.69 − 10.75 and star formation rates in the youngest age bin in the range log 10 (SFR / (M ⊙ yr − 1)) ∼ 0.39 − 1.46 , placing the sample galaxies on the massive end of the star-forming main sequence in this redshift interval. In addition, three of the five galaxies have strong Ly α emissions, offering unique opportunities to study Ly α emitters at high redshift in future work. [ABSTRACT FROM AUTHOR]

The epoch of reionization (EoR) offers a unique window into the dawn of galaxy formation, through which high-redshift galaxies can be studied by observations of both themselves and their impact on the intergalactic medium. Line intensity mapping (LIM) promises to explore cosmic reionization and its driving sources by measuring intensity fluctuations of emission lines tracing the cosmic gas in varying phases. Using LIMFAST, a novel seminumerical tool designed to self-consistently simulate LIM signals of multiple EoR probes, we investigate how building blocks of galaxy formation and evolution theory, such as feedback-regulated star formation and chemical enrichment, might be studied with multitracer LIM during the EoR. On galaxy scales, we show that the star formation law and the feedback associated with star formation can be indicated by both the shape and redshift evolution of LIM power spectra. For a baseline model of metal production that traces star formation, we find that lines highly sensitive to metallicity are generally better probes of galaxy formation models. On larger scales, we demonstrate that inferring ionized bubble sizes from cross-correlations between tracers of ionized and neutral gas requires a detailed understanding of the astrophysics that shape the line luminosity–halo mass relation. Despite various modeling and observational challenges, wide-area, multitracer LIM surveys will provide important high-redshift tests for the fundamentals of galaxy formation theory, especially the interplay between star formation and feedback by accessing statistically the entire low-mass population of galaxies as ideal laboratories, complementary to upcoming surveys of individual sources by new-generation telescopes. [ABSTRACT FROM AUTHOR]

We present LIMFAST, a seminumerical code for simulating high-redshift galaxy formation and cosmic reionization as revealed by multitracer line intensity mapping (LIM) signals. LIMFAST builds upon and extends the 21cmFAST code widely used for 21 cm cosmology by implementing state-of-the-art models of galaxy formation and evolution. The metagalactic radiation background, including the production of various star formation lines, together with the 21 cm line signal tracing the neutral intergalactic medium (IGM), is self-consistently described by photoionization modeling and stellar population synthesis coupled to the galaxy formation model. We introduce basic structure and functionalities of the code, and demonstrate its validity and capabilities by showing broad agreements between the predicted and observed evolution of cosmic star formation, IGM neutral fraction, and metal enrichment. We also present the LIM signals of 21 cm, Ly α, H α, H β, [O ii ], and [O iii ] lines simulated by LIMFAST, and compare them with results from the literature. We elaborate on how several major aspects of our modeling framework, including models of star formation, chemical enrichment, and photoionization, may impact different LIM observables and thus become testable once applied to observational data. LIMFAST aims at being an efficient and resourceful tool for intensity mapping studies in general, exploring a wide range of scenarios of galaxy evolution and reionization and frequencies over which useful cosmological signals can be measured. [ABSTRACT FROM AUTHOR]

Feedback likely plays a crucial role in resolving discrepancies between observations and theoretical predictions of dwarf galaxy properties. Stellar feedback was once believed to be sufficient to explain these discrepancies, but it has thus far failed to fully reconcile theory and observations. The recent discovery of energetic galaxy-wide outflows in dwarf galaxies hosting active galactic nuclei (AGNs) suggests that AGN feedback may have a larger role in the evolution of dwarf galaxies than previously suspected. In order to assess the relative importance of stellar versus AGN feedback in these galaxies, we perform a detailed Keck/KCWI optical integral field spectroscopic study of a sample of low-redshift star-forming (SF) dwarf galaxies that show outflows in ionized gas in their Sloan Digital Sky Survey spectra. We characterize the outflows and compare them to observations of AGN-driven outflows in dwarfs. We find that SF dwarfs have outflow components that have comparable widths (W 80) to those of outflows in AGN dwarfs, but are much less blueshifted, indicating that SF dwarfs have significantly slower outflows than their AGN counterparts. Outflows in SF dwarfs are spatially resolved and significantly more extended than those in AGN dwarfs. The mass-loss, momentum, and energy rates of star-formation-driven outflows are much lower than those of AGN-driven outflows. Our results indicate that AGN feedback in the form of gas outflows may play an important role in dwarf galaxies and should be considered along with SF feedback in models of dwarf galaxy evolution. [ABSTRACT FROM AUTHOR]

The feedback from the accretion of central supermassive black holes (SMBHs) is a hot topic in the coevolution of SMBHs and their host galaxies. By tracing the large-scale outflow using the line profile and bulk velocity shift of [O iii ] λ 5007, the evolutionary role of outflow is studied here on a large sample of 221 type 2 quasars (QSO2s) extracted from Reyes et al. By following our previous study on local Seyfert 2 galaxies, the current spectral analysis on the Sloan Digital Sky Survey spectroscopic database enables us to arrive at the following results: (1) by using the Lick indices, we confirm that QSO2s are, on average, more frequently associated with younger stellar populations than Seyfert galaxies; (2) QSO2s with a stronger outflow tend to be associated with a younger stellar population, which implies a coevolution between the feedback from SMBHs and the host in QSO2s; (3) although occupied at the high L bol/ L Edd end, the QSO2s follow the L bol/ L Edd- D n (4000) sequence established from local, less-luminous Seyfert galaxies, which suggests a decrease of the accretion activity of SMBHs and also of feedback as the circumnuclear stellar population continuously ages. [ABSTRACT FROM AUTHOR]

We present results on the properties of extreme gas outflows in massive (M * ∼ 1011 M ⊙), compact, starburst (star formation rate, SFR∼ 200 M ⊙ yr−1) galaxies at z = 0.4–0.7 with very high star formation surface densities (ΣSFR ∼ 2000 M ⊙ yr−1 kpc−2). Using optical Keck/HIRES spectroscopy of 14 HizEA starburst galaxies, we identify outflows with maximum velocities of 820–2860 km s−1. High-resolution spectroscopy allows us to measure precise column densities and covering fractions as a function of outflow velocity and characterize the kinematics and structure of the cool gas outflow phase (T ∼ 104 K). We find substantial variation in the absorption profiles, which likely reflects the complex morphology of inhomogeneously distributed, clumpy gas and the intricacy of the turbulent mixing layers between the cold and hot outflow phases. There is not a straightforward correlation between the bursts in the galaxies' star formation histories and their wind absorption line profiles, as might naively be expected for starburst-driven winds. The lack of strong Mg ii absorption at the systemic velocity is likely an orientation effect, where the observations are down the axis of a blowout. We infer high mass outflow rates of ∼50–2200 M ⊙ yr−1, assuming a fiducial outflow size of 5 kpc, and mass loading factors of η ∼ 5 for most of the sample. While these values have high uncertainties, they suggest that starburst galaxies are capable of ejecting very large amounts of cool gas that will substantially impact their future evolution. [ABSTRACT FROM AUTHOR]

We present visual classifications of merger-induced tidal disturbances in 143 M * ∼ 1011 M ⊙ post-starburst galaxies at z ∼ 0.7 identified in the SQuIGG 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 ∼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. [ABSTRACT FROM AUTHOR]

We use medium-resolution JWST/NIRSpec observations from the Cosmic Evolution Early Release Science Survey to place the first constraints on dust attenuation and star formation based on Paschen lines for a sizable sample of 63 galaxies at redshifts z = 1.0–3.1. Our analysis indicates strong correlations between the Balmer decrement, H α /H β, and line ratios that include Paschen lines (i.e., Pa α /H β, Pa β /H β, and the Paschen decrement, Pa α /Pa β), suggesting that the former is sensitive to the overall dust obscuration toward H ii regions in high-redshift galaxies. The line ratios are used to derive nebular reddening, E (B − V)neb, and star formation rates (SFRs). There is marginal evidence that the SFRs deduced from Paschen lines may exceed by ≈25% those derived from Balmer lines alone, suggesting the presence of star formation that is optically thick in Balmer lines, though deeper observations are needed to confirm this result. Using the Paschen-line constraints on the bolometric SFRs, we reevaluate the relationship between dust obscuration and UV spectral slope, and find a reddening of the UV continuum that, on average, follows the SMC extinction curve. This analysis highlights the need for deeper spectroscopy of more representative samples to evaluate nebular dust attenuation and bolometric SFRs in high-redshift galaxies, and their relationship to the reddening of the UV continuum. [ABSTRACT FROM AUTHOR]

We combine data sets from the CGM2 and CASBaH surveys to model a transition point, R cross, between circumgalactic and intergalactic media (CGM and IGM, respectively). In total, our data consist of 7244 galaxies at z < 0.5 with precisely measured spectroscopic redshifts, all having impact parameters of 0.01–20 comoving Mpc from 28 QSO sightlines with high-resolution UV spectra that cover H i Ly α. Our best-fitting model is a two-component model that combines a 3D absorber–galaxy cross-correlation function with a simple Gaussian profile at inner radii to represent the CGM. By design, this model gives rise to a determination of R cross as a function of galaxy stellar mass, which can be interpreted as the boundary between the CGM and IGM. For galaxies with 108 ≤ M ⋆/ M ⊙ ≤ 1010.5, we find that R cross(M ⋆) ≈ 2.0 ± 0.6 R vir. Additionally, we find excellent agreement between R cross(M ⋆) and the theoretically determined splashback radius for galaxies in this mass range. Overall, our results favor models of galaxy evolution at z < 0.5 that distribute T ≈ 104K gas to distances beyond the virial radius. [ABSTRACT FROM AUTHOR]

We investigate the stellar mass–black hole mass (  * –  BH ) relation with type 1 active galactic nuclei (AGNs) down to  BH = 10 7 M ⊙ , corresponding to a ≃ −21 absolute magnitude in rest-frame ultraviolet, at z = 2–2.5. Exploiting the deep and large-area spectroscopic survey of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX), we identify 66 type 1 AGNs with  BH ranging from 107–1010 M ⊙ that are measured with single-epoch virial method using C iv emission lines detected in the HETDEX spectra.  * of the host galaxies are estimated from optical to near-infrared photometric data taken with Spitzer, the Wide-field Infrared Survey Explorer, and ground-based 4–8 m class telescopes by CIGALE spectral energy distribution (SED) fitting. We further assess the validity of SED fitting in two cases by host-nuclear decomposition performed through surface brightness profile fitting on spatially resolved host galaxies with the James Webb Space Telescope/NIRCam CEERS data. We obtain the  * –  BH relation covering the unexplored low-mass ranges of  BH ∼ 10 7 – 10 8 M ⊙ , and conduct forward modeling to fully account for the selection biases and observational uncertainties. The intrinsic  * –  BH relation at z ∼ 2 has a moderate positive offset of 0.52 ± 0.14 dex from the local relation, suggestive of more efficient black hole growth at higher redshift even in the low-mass regime of  BH ∼ 10 7 – 10 8 M ⊙ . Our  * –  BH relation is inconsistent with the  BH suppression at the low-  * regime predicted by recent hydrodynamic simulations at a 98% confidence level, suggesting that feedback in the low-mass systems may be weaker than those produced in hydrodynamic simulations. [ABSTRACT FROM AUTHOR]

We present a Keck/MOSFIRE rest-optical composite spectrum of 16 typical gravitationally lensed star-forming dwarf galaxies at 1.7 ≲ z ≲ 2.6 (z mean = 2.30), all chosen independent of emission-line strength. These galaxies have a median stellar mass of log (M * / M ⊙) med = 8.29 − 0.43 + 0.51 and a median star formation rate of S F R H α m e d = 2.25 − 1.26 + 2.15 M ⊙ y r − 1 . We measure the faint electron-temperature-sensitive [O iii ] λ 4363 emission line at 2.5 σ (4.1 σ) significance when considering a bootstrapped (statistical-only) uncertainty spectrum. This yields a direct-method oxygen abundance of 12 + log (O / H) direct = 7.88 − 0.22 + 0.25 ( 0.15 − 0.06 + 0.12 Z ⊙ ). We investigate the applicability at high z of locally calibrated oxygen-based strong-line metallicity relations, finding that the local reference calibrations of Bian et al. best reproduce (≲0.12 dex) our composite metallicity at fixed strong-line ratio. At fixed M *, our composite is well represented by the z ∼ 2.3 direct-method stellar mass—gas-phase metallicity relation (MZR) of Sanders et al. When comparing to predicted MZRs from the IllustrisTNG and FIRE simulations, having recalculated our stellar masses with more realistic nonparametric star formation histories (log (M * / M ⊙) med = 8.92 − 0.22 + 0.31) , we find excellent agreement with the FIRE MZR. Our composite is consistent with no metallicity evolution, at fixed M * and SFR, of the locally defined fundamental metallicity relation. We measure the doublet ratio [O ii ] λ 3729/[O ii ] λ 3726 = 1.56 ± 0.32 (1.51 ± 0.12) and a corresponding electron density of n e = 1 − 0 + 215 cm − 3 ( n e = 1 − 0 + 74 cm − 3 ) when considering the bootstrapped (statistical-only) error spectrum. This result suggests that lower-mass galaxies have lower densities than higher-mass galaxies at z ∼ 2. [ABSTRACT FROM AUTHOR]

Galaxy formation and evolution are regulated by the feedback from galactic winds. Absorption lines provide the most widely available probe of winds. However, since most data only provide information integrated along the line of sight, they do not directly constrain the radial structure of the outflows. In this paper, we present a method to directly measure the gas electron density in outflows (n e ), which in turn yields estimates of outflow cloud properties (e.g., density, volume filling factor, and sizes/masses). We also estimate the distance (r n ) from the starburst at which the observed densities are found. We focus on 22 local star-forming galaxies primarily from the COS Legacy Archive Spectroscopic SurveY (CLASSY). In half of them, we detect absorption lines from fine-structure excited transitions of Si ii (i.e., Si ii *). We determine n e from relative column densities of Si ii and Si ii *, given Si ii * originates from collisional excitation by free electrons. We find that the derived n e correlates well with the galaxy's star formation rate per unit area. From photoionization models or assuming the outflow is in pressure equilibrium with the wind fluid, we get r n ∼ 1–2 r * or ∼5 r *, respectively, where r * is the starburst radius. Based on comparisons to theoretical models of multiphase outflows, nearly all of the outflows have cloud sizes large enough for the clouds to survive their interaction with the hot wind fluid. Most of these measurements are the first ever for galactic winds detected in absorption lines and, thus, will provide important constraints for future models of galactic winds. [ABSTRACT FROM AUTHOR]

We investigate the connection between the regulation of star formation and the cycling of baryons both within and in and out of galaxies. We use idealized numerical simulations of Milky Way–mass galaxies, in which we vary the galaxy morphology and stellar feedback strength. By following individual gas parcels through the disk, spiral arms, and massive star-forming clumps, we quantify how gas moves through the different phases of the interstellar medium (ISM) and forms stars. We show that the residence time of gas in the dense ISM phase (τ SF), the nature of spiral arms, and the clump properties depend on both the galaxy morphology and stellar feedback. We quantify signatures of the baryon cycle within galaxies using the temporal and spatial power spectrum density (PSD) of the star formation rate (SFR). Stronger stellar feedback leads to more bursty star formation while the correlation timescale of the SFH is longer, because stronger feedback dissolves the dense ISM phase, leading to a more homogeneous ISM and a decrease in τ SF. The bulge strength has a similar effect: the deep gravitational potential in a bulge-dominant galaxy imposes a strong shear force that breaks apart gas clumps in the ISM; this subsequently inhibits the fragmentation of gas and therefore the star formation in the disk, leading to a decrease in the spatial power on scales of ∼1 kpc. We conclude that measurements of the temporal and spatial PSD of the SFR can provide constraints on the baryon cycle and the star formation process. [ABSTRACT FROM AUTHOR]

We present the results of a systematic search for candidate quiescent galaxies in the distant universe in 11 JWST fields with publicly available observations collected during the first 3 months of operations and covering an effective sky area of ∼145 arcmin2. We homogeneously reduce the new JWST data and combine them with existing observations from the Hubble Space Telescope. We select a robust sample of ∼80 candidate quiescent and quenching galaxies at 3 < z < 5 using two methods: (1) based on their rest-frame UVJ colors, and (2) a novel quantitative approach based on Gaussian mixture modeling of the near-UV − U, U − V, and V − J rest-frame color space, which is more sensitive to recently quenched objects. We measure comoving number densities of massive (M ⋆ ≥ 1010.6 M ⊙) quiescent galaxies consistent with previous estimates relying on ground-based observations, after homogenizing the results in the literature with our mass and redshift intervals. However, we find significant field-to-field variations of the number densities up to a factor of 2–3, highlighting the effect of cosmic variance and suggesting the presence of overdensities of red quiescent galaxies at z > 3, as could be expected for highly clustered massive systems. Importantly, JWST enables the robust identification of quenching/quiescent galaxy candidates at lower masses and higher redshifts than before, challenging standard formation scenarios. All data products, including the literature compilation, are made publicly available. [ABSTRACT FROM AUTHOR]

We explore how the fraction of quenched galaxies changes in groups of galaxies with respect to the distance to the center of the group, redshift, and stellar mass to determine the dominant process of environmental quenching in 0.2 < z < 0.8 groups. We use new UV data from the UVCANDELS project in addition to existing multiband photometry to derive new galaxy physical properties of the group galaxies from the zCOSMOS 20 k group catalog. Limiting our analysis to a complete sample of log (M */ M ⊙) > 10.56 group galaxies, we find that the probability of being quenched increases slowly with decreasing redshift, diverging from the stagnant field galaxy population. A corresponding analysis on how the probability of being quenched increases with time within groups suggests that the dominant environmental quenching process is characterized by slow (∼Gyr) timescales. We find a quenching time of approximately 4.91 − 1.47 + 0.91 Gyr, consistent with the slow processes of strangulation and delayed-then-rapid quenching although more data are needed to confirm this result. [ABSTRACT FROM AUTHOR]

We combine an unprecedented MaNGA sample of over 3000 passive galaxies in the stellar mass range 109–1012 M ⊙ with the Sloan Digital Sky Survey group catalog by Tinker to quantify how central and satellite formation, quantified by radial profiles in stellar age, [Fe/H], and [Mg/Fe], depends on the stellar mass of the galaxy (M *) and the mass of the host halo (M h ). After controlling for M * and M h , the stacked spectra of centrals and satellites beyond the effective radius (r e ) show small, yet significant differences in multiple spectral features at the 1% level. According to spectral fitting with the code alf, a primary driver of these differences appears to be [Mg/Fe] variations, suggesting that stellar populations in the outskirts of satellites formed more rapidly than the outer populations of centrals. To probe the physical mechanisms that may be responsible for this signal, we examined how satellite stellar populations depend on M h . We find that satellites in high- M h halos show older stellar ages, lower [Fe/H], and higher [Mg/Fe] compared to satellites in low- M h halos, especially for M * = 109.5–1010.5 M ⊙. These signals lend support to environmentally driven processes that quench satellite galaxies, although variations in the merger histories of central and satellite galaxies also emerge as a viable explanation. [ABSTRACT FROM AUTHOR]

Radio activity in AGN (Active Galactic Nuclei) produce feedback on the host galaxy via the impact of the relativistic jets on the circumnuclear gas. Although radio jets can reach up to several times the optical radius of the host galaxy, in this review we focus on the observation of the feedback deposited locally in the central region of the host galaxies, in the form of outflows due to the jet-gas interaction. We begin by discussing how galaxy mergers and interactions are the most favored scenario for triggering radio AGN after gas accretion to the nuclear supermassive black hole and star formation enhancement in the nuclear region, observed in particular in the most luminous sources. We then discuss observational signatures of the process of jet-gas coupling, in particular the resulting outflows and their effects on the host galaxy. These include the presence of shock signatures and the detection of outflows not only along the radio jet but perpendicular to it in many sources. Although most of the studies are done via the observation of ionized gas, molecular gas is also being increasingly observed in outflow, contributing to the bulk of the mass outflow rate. Even though most radio sources present outflow kinetic powers that do not reach 1 % L b o l , and thus do not seem to provide an immediate impact on the host galaxy, they act to heat the ISM gas, preventing star formation, slowing the galaxy mass build-up process and limiting the stellar mass growth, in a "maintenance mode" feedback. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the benefits of teaming up data from the radio to the far-infrared (FIR) regime for the characterization of dusty star-forming galaxies (DSFGs). These galaxies are thought to be the star-forming progenitors of local massive quiescent galaxies and to play a pivotal role in the reconstruction of the cosmic star formation rate density up to high redshift. Due to their dust-enshrouded nature, DSFGs are often invisible in the near-infrared/optical/UV bands. Therefore, they necessitate observations at longer wavelengths, primarily the FIR band, where dust emission occurs, and the radio band, which is not affected by dust absorption. Combining data from these two spectral windows makes it possible to characterize even the dustiest objects, enabling the retrieval of information about their age, dust temperature, and star-formation status, and facilitates the differentiation between various galaxy populations that evolve throughout cosmic history. Despite the detection of faint radio sources being a challenging task, this study demonstrates that an effective strategy to build statistically relevant samples of DSFGs would be reaching deep sensitivities in the radio band, even restricted to smaller areas, and then combining these radio observations with FIR/submm data. Additionally, this paper quantifies the improvement in the spectral energy distribution (SED) reconstruction of DSFGs by incorporating ALMA band measurements, in particular, in its upgraded status thanks to the anticipated Wideband Sensitivity Upgrade.

We investigate size variation with rest-frame wavelength for star-forming galaxies based on the second James Webb Space Telescope Advanced Deep Extragalactic Survey data release. Star-forming galaxies are typically smaller at longer wavelengths from the UV to the near-IR at z < 3.5, especially for more massive galaxies, indicating the inside-out assembly with in situ star formation if ignoring dust attenuation. The size variation with wavelength shows a strong dependence on stellar mass and shows little or no dependence on redshift, specific star formation rate, and galaxy environment. This suggests that the size growth of star-forming galaxies is a self-regulated process primarily governed by stellar mass. We model size as a function of both mass and redshift simultaneously, obtaining ${R}_{{\rm{e}}}\propto {M}_{* }^{0.23}{(1+z)}^{-1.04}$ at a wavelength of 0.45 μ m, and ${R}_{{\rm{e}}}\propto {M}_{* }^{0.20}{(1+z)}^{-1.08}$ at 1.0 μ m. Based on this size evolution and the star formation main sequence from the literature, we obtain the locus of typical size growth for individual galaxies of different masses on the mass–size plane. The moving trend of galaxies on the mass–size plane, which indicates the slopes of their locus, strongly correlates with the size ratio between 0.45 μ m and 1.0 μ m, supporting the idea that the size variation with wavelength provides important information on the size growth of galaxies on short timescales.

We study the stellar properties of a sample of simulated ultradiffuse galaxies (UDGs) with stellar mass M _⋆ = 10 ^7.5 –10 ^9 M _⊙ , selected from the TNG50 simulation, where UDGs form mainly in high-spin dwarf-mass halos. We divide our sample into star-forming and quenched UDGs, finding good agreement with the stellar assembly history measured in observations. Star-forming UDGs and quenched UDGs with M _⋆ ≥ 10 ^8 M _⊙ in our sample are particularly inefficient at forming stars, having 2–10 times less stellar mass than non-UDGs for the same virial mass halo. These results are consistent with recent mass inferences in UDG samples and suggest that the most inefficient UDGs arise from a late assembly of the dark matter mass followed by a stellar growth that is comparatively slower (for star-forming UDGs) or that was interrupted due to environmental removal of the gas (for quenched UDGs). Regardless of efficiency, UDGs are 60% poorer in [Fe/H] than the population of non-UDGs at a fixed stellar mass, with the most extreme objects having metal content consistent with the simulated mass–metallicity relation at z ∼ 2. Quenched UDGs stop their star formation in shorter timescales than non-UDGs of similar mass and are, as a consequence, alpha enhanced with respect to non-UDGs. We identify metallicity profiles in UDGs as a potential avenue to distinguish between different formation paths for these galaxies, where gentle formation as a result of high-spin halos would present well-defined declining metallicity radial profiles while powerful-outflows or tidal stripping formation models would lead to flatter or constant metallicity as a function of radius due to the inherent mixing of stellar orbits.

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 .

We have used public JWST/NIRSpec and JWST/NIRCam observations from the CEERS and JADES surveys in order to analyze the star-forming main sequence (SFMS) over the redshift range 1.4 ≤ z < 7. We calculate the star formation rates (SFRs) of the galaxy sample using three approaches: Balmer line luminosity, spectral energy distribution (SED) fitting, and UV luminosity. We find a larger degree of scatter about the SFMS using the Balmer-based SFRs compared to the UV-based SFRs. Because these SFR indicators are sensitive to star formation on different timescales, the difference in scatter may be evidence of bursty star formation histories in the early Universe. We additionally compare the H α -to-UV luminosity ratio ( L (H α )/ ν L _ν _,1600 ) for individual galaxies in the sample and find that 29%–52% of the ratios across the sample are poorly described by predictions from a smooth star formation history. Measuring the burstiness of star formation in the early Universe has multiple significant implications, such as deriving accurate physical parameters from SED fitting, explaining the evolution of the UV luminosity function, and providing constraints for subgrid models of feedback in simulations of galaxy formation and evolution.

The existence of a population of massive quiescent galaxies with little to no star formation poses a challenge to our understanding of galaxy evolution. The physical process that quenched the star formation in these galaxies is debated, but the most popular possibility is that feedback from supermassive black holes lifts or heats the gas that would otherwise be used to form stars. In this paper, we evaluate this idea in two ways. First, we compare the cumulative growth in the cosmic inventory of the total stellar mass in quiescent galaxies to the corresponding growth in the amount of kinetic energy carried by radio jets. We find that these two inventories are remarkably well-synchronized, with about 50% of the total amounts being created in the epoch from z ≈ 1 to 2. We also show that these agree extremely well with the corresponding growth in the cumulative number of major mergers that result in massive (>10 ^11 M _ʘ ) galaxies. We therefore argue that major mergers trigger the radio jets and also transform the galaxies from disks to spheroids. Second, we evaluate the total amount of kinetic energy delivered by jets and compare it to the baryonic binding energy of the galaxies. We find the jet kinetic energy is more than sufficient to quench star formation, and the quenching process should be more effective in more massive galaxies. We show that these results are quantitatively consistent with recent measurements of the Sunyaev–Zel’dovich effect seen in massive galaxies at z ≈ 1.

The formation pathways of lenticular galaxies (S0s) in field environments remain a matter of debate. We utilize the cosmological hydrodynamic simulation, NewHorizon , to investigate the issue. We select two massive star formation quenched S0s as our main sample. By closely tracing their physical and morphological evolution, we identify two primary formation channels: mergers and counterrotating gas accretion. The former induces central gas inflow due to gravitational and hydrodynamic torques, triggering active central star formation, which quickly depletes the gas of the galaxy. Counterrotating gas accretion overall has a similar outcome but more exclusively through hydrodynamic collisions between the preexisting and newly accreted gas. Both channels lead to S0 morphology, with gas angular momentum cancellation being a crucial mechanism. These formation pathways quench star formation on a short timescale (

We combine JWST/NIRCam and Subaru/MOIRCS dual Pa β +H α narrowband imaging to trace the dust attenuation and the star formation activities of a sample of 43 H α emitters at the core of one of the most massive and best-studied clusters in formation at the cosmic noon: the Spiderweb protocluster at z = 2.16. We find that most H α emitters display Pa β /H α ratios compatible with Case B recombination conditions, which translates into nebular extinction values ranging at A _V ≈ 0–3 mag, and dust corrected Pa β star formation rates consistent with coeval main sequence field galaxies at fixed stellar mass ( $9.4\lt \mathrm{log}\ {{M}}_{* }/{{M}}_{\odot }\lt 11.0$ ) during this cosmic epoch. Furthermore, we investigate possible environmental impacts on dust extinction across the protocluster large-scale structure and find no correlation between the dustiness of its members and environmental proxies such as phase-space position, clustercentric radius, or local density. These results support the scenario for which dust production within the main galaxy population of this protocluster is driven by secular star formation activities fueled by smooth gas accretion across its large-scale structure. This downplays the role of gravitational interactions in boosting star formation and dust production within the Spiderweb protocluster, in contrast with observations in higher redshift and less evolved protocluster cores.

We report the initial result of our Pa β narrowband imaging on a protocluster with the JWST Near Infrared Camera (NIRCam). As NIRCam enables deep narrowband imaging of rest-frame near-infrared lines at z > 1, we target one of the most studied protoclusters, the Spiderweb protocluster at z = 2.16, in which previous studies have confirmed more than a hundred member galaxies. The NIRCam F405N narrowband filter covers in the Pa β line the protocluster redshift given by known protocluster members, allowing for the search for new member candidates. The weight-corrected color–magnitude diagram obtained 57 sources showing narrowband excesses, 41 of which satisfy further color selection criteria for limiting the sample to Pa β emitter candidates at z ∼ 2.16, and 24 of them do not have H α emitter counterparts. The Pa β emitter candidates appear to follow the spatial distribution of known protocluster members; however, follow-up spectroscopic confirmation is required. Only 17 out of 58 known H α -emitting cluster members are selected as Pa β emitters in the current data, albeit the rest fall out of the narrowband selection owing to their small Pa β equivalent widths. We derive the Pa β luminosity function in the Spiderweb protocluster, showing a normalization density of $\mathrm{log}{\phi }^{* }=-2.53\pm 0.15$ at a characteristic Pa β luminosity of $\mathrm{log}{L}^{* }=42.33\pm 0.17$ . Furthermore, we examine the possibility of detecting faint line emitters visible only in the narrowband image but find no promising candidates.

We report the Hubble Space Telescope Wide Field Camera 3 G141 grism slitless spectroscopy observation of the core region of the Spiderweb protocluster at z = 2.16. We analyzed the spectra of all objects in a $\sim 2\times 2\,{\mathrm{arcmin}}^{2}$ field of view and identified 40 protocluster members, recovering 19 previously identified H α emitters in addition to revealing 21 new members. The spectra allowed us to identify 11 galaxies with quiescent spectra. In all, 3 galaxies with quiescent spectra are possibly still star forming according to spectral energy distribution fitting, indicating a possible leftover or dust-obscured star formation. We estimate a quiescent fraction of ∼50% for M _⋆ > 10 ^11 M _⊙ . About half of the quiescent galaxies possibly host an active galactic nucleus (AGN), hinting at AGN’s key role in quenching galaxies in the protocluster environment. These quiescent galaxies have relatively more compact and concentrated light profiles than the star-forming members, but they are not yet as bulge dominated as local ellipticals. These results are consistent with previous studies that indicate the Spiderweb protocluster is in the maturing stage, with a red sequence that has begun forming.

We present rest-frame optical spectra from Keck/MOSFIRE and Keck/NIRES of 16 candidate ultramassive galaxies targeted as part of the Massive Ancient Galaxies at z > 3 Near-Infrared Survey (MAGAZ3NE). These candidates were selected to have photometric redshifts 3 ≲ z _phot 11.7, and well-sampled photometric spectral energy distributions (SEDs) from the UltraVISTA and VIDEO surveys. In contrast to previous spectroscopic observations of blue star-forming and poststarburst ultramassive galaxies, candidates in this sample have very red SEDs implying significant dust attenuation, old stellar ages, and/or active galactic nuclei (AGN). Of these galaxies, eight are revealed to be heavily dust-obscured 2.0 < z < 2.7 galaxies with strong emission lines, some showing broad features indicative of AGN, three are Type I AGN hosts at z > 3, one is a z ∼ 1.2 dusty galaxy, and four galaxies do not have a confirmed spectroscopic redshift. In fact, none of the sample has ∣ z _spec − z _phot ∣ < 0.5, suggesting difficulties for photometric redshift programs in fitting similarly red SEDs. The prevalence of these red interloper galaxies suggests that the number densities of high-mass galaxies are overestimated at z ≳ 3 in large photometric surveys, helping to resolve the “impossibly early galaxy problem” and leading to much better agreement with cosmological galaxy simulations. A more complete spectroscopic survey of ultramassive galaxies is required to pin down the uncertainties on their number densities in the early Universe.

We use a sample of 73 simulated satellite and central dwarf galaxies spanning a stellar mass range of 10 ^5.3 –10 ^9.1 M _⊙ to investigate the origin of their stellar age gradients. We find that dwarf galaxies often form their stars “inside-out,” i.e., the stars form at successively larger radii over time. However, the oldest stars get reshuffled beyond the star-forming radius by fluctuations in the gravitational potential well caused by stellar feedback (the same mechanisms that cause dwarfs to form dark matter cores). The result is that many dwarfs appear to have an “outside-in” age gradient at z = 0, with younger stellar populations more centrally concentrated. However, for the reshuffled galaxies with the most extended star formation, young stars can form out to the large radii to which the old stars have been reshuffled, erasing the age gradient. We find that major mergers do not play a significant role in setting the age gradients of dwarfs. We find similar age gradient trends in satellites and field dwarfs, suggesting that environment plays only a minor role, if any. Finally, we find that the age gradient trends are imprinted on the galaxies at later times, suggesting that the stellar reshuffling dominates after the galaxies have formed 50% of their stellar mass. The later reshuffling is at odds with results from the fire-2 simulations. Hence, age gradients offer a test of current star formation and feedback models that can be probed via observations of resolved stellar populations.

We present a statistical study of 180 dust continuum sources identified in 33 massive cluster fields by the Atacama Large Millimeter/submillimeter Array Lensing Cluster Survey (ALCS) over a total of 133 arcmin ^2 area, homogeneously observed at 1.2 mm. ALCS enables us to detect extremely faint millimeter sources by lensing magnification, including near-infrared (NIR) dark objects showing no counterparts in existing Hubble Space Telescope and Spitzer images. The dust continuum sources belong to a blind sample ( N = 141) with signal-to-noise ratio (S/N) ≳ 5.0 (a purity of >0.99) or a secondary sample ( N = 39) with S/N = 4.0–5.0 screened by priors. With the blind sample, we securely derive 1.2 mm number counts down to ∼7 μ Jy, and find that the total integrated 1.2 mm flux is ${20.7}_{-6.5}^{+8.5}$ Jy deg ^−2 , resolving ≃80% of the cosmic infrared background light. The resolved fraction varies by a factor of 0.6–1.1 due to the completeness correction depending on the spatial size of the millimeter emission. We also derive infrared (IR) luminosity functions (LFs) at z = 0.6–7.5 with the $1/{V}_{\max }$ method, finding the redshift evolution of IR LFs characterized by positive luminosity and negative density evolution. The total (= UV + IR) cosmic star formation rate density (SFRD) at z > 4 is estimated to be ${161}_{-21}^{+25}$ % of the Madau and Dickinson measurements mostly based on rest-frame UV surveys. Although our general understanding of the cosmic SFRD is unlikely to change beyond a factor of 2, these results add to the weight of evidence for an additional (≈60%) SFRD component contributed by the faint millimeter population, including NIR-dark objects.

Dark matter (DM) bars that shadow stellar bars have been previously shown to form in idealized simulations of isolated disk galaxies, but have yet to be studied in a fully cosmological context. In this work, we analyze a population of disk galaxies within the TNG50 simulation to determine the characteristics of their dark bars. We estimate bar strength and orientation using both the in-plane Fourier A _2 density moments and the quadrupolar coefficients of the spherical harmonic basis function expansions of the density. We additionally present two novel methods for measuring the bar pattern speed Ω _p and rotation axis orientation using these coefficients, and apply them to one sample galaxy located in a TNG50 subbox. Consistent with isolated simulations, DM bars are shorter than their stellar counterparts and are 75% weaker in A _2 . DM bars dominate the shape of the inner halo potential and are apparent in the time series of quadrupolar coefficients. In our selected subbox galaxy, the stellar and dark bars remain co-aligned throughout the last 8 Gyr and have identical Ω _p . Pattern speed Ω _p evolves considerably over the last 8 Gyr, consistent with torques on the bars due to dynamical friction and gas accretion, and is seen to increase following a merger at t _lb = 1.5 Gyr. Rather than remaining static in time, the bar rotation axis displays both precession and nutation possibly caused by torques outside the plane of rotation. We find that the shape of the stellar and DM mass distributions are tightly correlated with Ω _p .

The exceptional spectra of the most luminous z > 10 sources observed so far have challenged our understanding of early galaxy evolution, requiring a new observational benchmark for meaningful interpretation. As such, we construct spectroscopic templates representative of high-redshift, star-forming populations, using 482 confirmed sources at z = 5.0−12.9 with JWST/NIRSpec prism observations, and report on their average properties. We find z = 5−11 galaxies are dominated by blue UV continuum slopes ( β = −2.3 to −2.7) and reduced Balmer indices, characteristic of dust-poor and young systems, with a shift towards bluer slopes and younger ages with redshift. The evolution is mirrored by ubiquitous C iii ] detections across all redshifts (rest-frame equivalent widths of 5−14 Å), which increase in strength towards early times. Rest-frame optical lines reveal elevated ratios (O32 = 7–31, R23 = 5–8, and Ne3O2 = 1−2) and subsolar metallicities (log(O/H) = 7.3−7.9), typical of ionization conditions and metallicities rarely observed in z ∼ 0 populations. Within our sample, we identify 57 Ly α emitters, which we stack and compare to a matched sample of nonemitters. The former are characterized by more extreme ionizing conditions with enhanced C iii ], C iv , and He ii + [O iii ] line emission, younger stellar populations from Balmer jumps, and a more pristine interstellar medium seen through bluer UV slopes and elevated rest-frame optical line ratios. The novel comparison illustrates important intrinsic differences between the two populations, with implications for Ly α visibility. The spectral templates derived here represent a new observational benchmark with which to interpret high-redshift sources, lifting our constraints on their global properties to unprecedented heights and extending out to the earliest of cosmic times.

The Milky Way (MW) is surrounded by dozens of satellite galaxies, with six-dimensional (6D) phase-space information measured for over 80% of this population. The spatial distribution of these satellites is an essential probe of galaxy formation and for mapping the MW’s underlying dark matter distribution. Using measured 6D phase-space information of known MW satellites, we calculate orbital histories in a joint MW+LMC potential, including the gravitational influence of the LMC on all satellites and on the MW’s center of mass, and dynamical friction owing to both galaxies, to investigate the evolution of the MW’s cumulative radial profile. We conclude that radial profiles become more concentrated over time when we consider the LMC’s gravitational influence and the group infall of LMC-associated satellites. The MW’s radial distribution is consistently more concentrated at the present day and 1 and 2 Gyr ago compared to recent surveys of nearby MW-like systems. Compared to MW-mass hosts in cosmological, zoom-in simulations, we find the MW’s radial profile is also more concentrated than those of simulated counterparts; however, some overlap exists between simulation results and our analysis of the MW’s satellite distribution 2 Gyr ago, pre-LMC infall. Finally, we posit that radial profiles of simulated MW-mass analogs also hosting an LMC companion are likely to evolve similarly to our results, such that the accretion of a massive satellite along with its satellites will lead to a more concentrated radial profile as the massive satellite advances toward its host galaxy.

We explore the evolution of the ∼10 ^7 K hot gas in normal galaxies out to redshift = 0.5 (lookback time = 5 Gyr), using X-ray luminosity functions (XLFs) built from a sample of 575 normal galaxies with z < 0.6 detected in five high-galactic-latitude Chandra wide-field surveys. After estimating the emission due to the hot gas component (reducing the sample to ∼400 galaxies), we compared the XLF in three redshift bins ( z = 0.1, 0.3, and 0.5), finding increases in the number of galaxies per unit comoving volume from z = 0.1 to 0.3 and then from z = 0.3 to 0.5. These XLF changes suggest a significant (∼5 σ ) X-ray luminosity evolution of the hot gas, with L _X,GAS decreasing by a factor of 6–10 in the last 5 Gyr (from z = 0.5 to 0.1). The relative abundance of L _X,GAS ∼ 10 ^41 erg s ^−1 galaxies at higher z suggests that high -z , moderate -L _X,GAS galaxies may be the optimal target to solve the missing baryon problem. In early-type galaxies, this observational trend is qualitatively consistent with (but larger than) the expected time-dependent mass-loss rate in cooling flow models without active galactic nucleus feedback. In late-type galaxies, the observational trend is also qualitatively consistent with (but larger than) the effect of the z -dependent star formation rate.