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1. Unveiling the main sequence of galaxies at z ≥ 5 with the JWST : predictions from simulations

   https://doi.org/10.1093/mnras/stac2878  

   D’Silva, Jordan C. J. ; Lagos, Claudia D. P. ; Davies, Luke J. M. ; Lovell, Christopher C. ; Vijayan, Aswin P. ( October 2022 , Monthly Notices of the Royal Astronomical Society)

   We use two independent galaxy-formation simulations, flares, a cosmological hydrodynamical simulation, and shark, a semi-analytic model, to explore how well the JWST will be able to uncover the existence and parameters of the star-forming main sequence (SFS) at z = 5 → 10, i.e. shape, scatter, normalization. Using two independent simulations allows us to isolate predictions (e.g. stellar mass, star formation rate, SFR, luminosity functions) that are robust to or highly dependent on the implementation of the physics of galaxy formation. Both simulations predict that JWST can observe ≥70–90 per cent (for shark and flares, respectively) of galaxies up to z ∼ 10 (down to stellar masses of ${\approx}10^{8.3}\rm M_{\odot }$ and SFRs of ${\approx}10^{0.5}{\rm M}_{\odot }\,{\rm yr}^{-1}$) in modest integration times and given current proposed survey areas (e.g. the Web COSMOS 0.6 deg2) to accurately constrain the parameters of the SFS. Although both simulations predict qualitatively similar distributions of stellar mass and SFR. There are important quantitative differences, such as the abundance of massive, star-forming galaxies with flares predicting a higher abundance than shark; the early onset of quenching as a result of black hole growth in flares (at z ≈ 8), not seen in shark until much lower redshifts; and the implementation of synthetic photometry with flares predicting more JWST-detected galaxies (∼90 per cent) than shark (∼70 per cent) at z = 10. JWST observations will distinguish between these models, leading to a significant improvement upon our understanding of the formation of the very first galaxies.

    

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2. Trinity I: self-consistently modelling the dark matter halo–galaxy–supermassive black hole connection from z  = 0–10

   https://doi.org/10.1093/mnras/stac2633  

   Zhang ; Behroozi, Peter ; Volonteri, Marta ; Silk, Joseph ; Fan, Xiaohui ; Hopkins, Philip F ; Yang ; Aird, James ( November 2022 , Monthly Notices of the Royal Astronomical Society)

   We present Trinity, a flexible empirical model that self-consistently infers the statistical connection between dark matter haloes, galaxies, and supermassive black holes (SMBHs). Trinity is constrained by galaxy observables from 0 < z < 10 [galaxies’ stellar mass functions, specific and cosmic star formation rates (SFRs), quenched fractions, and UV luminosity functions] and SMBH observables from 0 < z < 6.5 (quasar luminosity functions, quasar probability distribution functions, active black hole mass functions, local SMBH mass–bulge mass relations, and the observed SMBH mass distributions of high-redshift bright quasars). The model includes full treatment of observational systematics [e.g. active galactic nucleus (AGN) obscuration and errors in stellar masses]. From these data, Trinity infers the average SMBH mass, SMBH accretion rate, merger rate, and Eddington ratio distribution as functions of halo mass, galaxy stellar mass, and redshift. Key findings include: (1) the normalization and the slope of the SMBH mass–bulge mass relation increases mildly from z = 0 to z = 10; (2) The best-fitting AGN radiative+kinetic efficiency is ∼0.05–0.06, but can be in the range ∼0.035–0.07 with alternative input assumptions; (3) AGNs show downsizing, i.e. the Eddington ratios of more massive SMBHs start to decrease earlier than those of lower mass objects; (4) The average ratio between average SMBH accretion rate and SFR is ∼10−3 for low-mass galaxies, which are primarily star-forming. This ratio increases to ∼10−1 for the most massive haloes below z ∼ 1, where star formation is quenched but SMBHs continue to accrete.

    

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3. Damped Lyα Absorbers in Star-forming Galaxies at z < 0.15 Detected with the Hubble Space Telescope and Implications for Galactic Evolution

   https://doi.org/10.3847/1538-4357/ac5fab  

   Kulkarni, Varsha P. ; Bowen, David V. ; Straka, Lorrie A. ; York, Donald G. ; Gupta, Neeraj ; Noterdaeme, Pasquier ; Srianand, Raghunathan ( April 2022 , The Astrophysical Journal)

   Abstract We report Hubble Space Telescope Cosmic Origins Spectrograph spectroscopy of 10 quasars with foreground star-forming galaxies at 0.02 < z < 0.14 within impact parameters of ∼1–7 kpc. We detect damped/sub-damped Ly α (DLA/sub-DLA) absorption in 100% of cases where no higher-redshift Lyman-limit systems extinguish the flux at the expected wavelength of Ly α absorption, obtaining the largest targeted sample of DLA/sub-DLAs in low-redshift galaxies. We present absorption measurements of neutral hydrogen and metals. Additionally, we present Green Bank Telescope 21 cm emission measurements for five of the galaxies (including two detections). Combining our sample with the literature, we construct a sample of 117 galaxies associated with DLA/sub-DLAs spanning 0 < z < 4.4, and examine trends between gas and stellar properties, and with redshift. The H i column density is anticorrelated with impact parameter and stellar mass. More massive galaxies appear to have gas-rich regions out to larger distances. The specific star formation rate (sSFR) of absorbing galaxies increases with redshift and decreases with M *, consistent with evolution of the star formation main sequence (SFMS). However, ∼20% of absorbing galaxies lie below the SFMS, indicating that some DLA/sub-DLAs trace galaxies with longer-than-typical gas-depletion timescales. Most DLA/sub-DLA galaxies with 21 cm emission have higher H i masses than typical galaxies with comparable M *. High M HI / M * ratios and high sSFRs in DLA/sub-DLA galaxies with M * < 10 9 M ⊙ suggest these galaxies may be gas-rich because of recent gas accretion rather than inefficient star formation. Our study demonstrates the power of absorption and emission studies of DLA/sub-DLA galaxies for extending galactic evolution studies to previously under-explored regimes of low M * and low SFR. 

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4. SQuIGGL⃗E : Studying Quenching in Intermediate-z Galaxies—Gas, AnguL⃗ar Momentum, and Evolution

   https://doi.org/10.3847/1538-4357/ac404a  

   Suess, Katherine A. ; Kriek, Mariska ; Bezanson, Rachel ; Greene, Jenny E. ; Setton, David ; Spilker, Justin S. ; Feldmann, Robert ; Goulding, Andy D. ; Johnson, Benjamin D. ; Leja, Joel ; et al ( February 2022 , The Astrophysical Journal)

   Abstract We describe the Studying Quenching in Intermediate- z Galaxies: Gas, angu L → ar momentum, and Evolution ( SQuIGG L ⃗ E ) survey of intermediate-redshift post-starburst galaxies. We leverage the large sky coverage of the Sloan Digital Sky Survey to select ∼ 1300 recently quenched galaxies at 0.5 < z ≤ 0.9 based on their unique spectral shapes. These bright, intermediate-redshift galaxies are ideal laboratories to study the physics responsible for the rapid quenching of star formation: they are distant enough to be useful analogs for high-redshift quenching galaxies, but low enough redshift that multiwavelength follow-up observations are feasible with modest telescope investments. We use the Prospector code to infer the stellar population properties and nonparametric star formation histories (SFHs) of all galaxies in the sample. We find that SQuIGG L ⃗ E galaxies are both very massive ( M * ∼ 10 11.25 M ⊙ ) and quenched, with inferred star formation rates ≲1 M ⊙ yr −1 , more than an order of magnitude below the star-forming main sequence. The best-fit SFHs confirm that these galaxies recently quenched a major burst of star formation: >75% of SQuIGG L ⃗ E galaxies formed at least a quarter of their total stellar mass in the recent burst, which ended just ∼200 Myr before observation. We find that SQuIGG L ⃗ E galaxies are on average younger and more burst-dominated than most other z ≲ 1 post-starburst galaxy samples. This large sample of bright post-starburst galaxies at intermediate redshift opens a wide range of studies into the quenching process. In particular, the full SQuIGG L ⃗ E survey will investigate the molecular gas reservoirs, morphologies, kinematics, resolved stellar populations, active galactic nucleus incidence, and infrared properties of this unique sample of galaxies in order to place definitive constraints on the quenching process. 

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5. CLEAR: The Evolution of Spatially Resolved Star Formation in Galaxies between 0.5 ≲ z ≲ 1.7 Using Hα Emission Line Maps

   https://doi.org/10.3847/1538-4357/ac8471  

   Matharu, Jasleen ; Papovich, Casey ; Simons, Raymond C. ; Momcheva, Ivelina ; Brammer, Gabriel ; Ji, Zhiyuan ; Backhaus, Bren E. ; Cleri, Nikko J. ; Estrada-Carpenter, Vicente ; Finkelstein, Steven L. ; et al ( September 2022 , The Astrophysical Journal)

   Using spatially resolved Hαemission line maps of star-forming galaxies, we study the spatial distribution of star formation over a wide range in redshift (0.5 ≲z≲ 1.7). Ourz∼ 0.5 measurements come from deep Hubble Space Telescope (HST) Wide Field Camera 3 G102 grism spectroscopy obtained as part of the CANDELS LyαEmission at Reionization Experiment. For star-forming galaxies with log(M_*/M_⊙) ≥ 8.96, the mean Hαeffective radius is 1.2 ± 0.1 times larger than that of the stellar continuum, implying inside-out growth via star formation. This measurement agrees within 1σwith those measured atz∼ 1 andz∼ 1.7 from the 3D-HST and KMOS^3Dsurveys, respectively, implying no redshift evolution. However, we observe redshift evolution in the stellar mass surface density within 1 kpc (Σ_1kpc). Star-forming galaxies atz∼ 0.5 with a stellar mass of log(M_*/M_⊙) = 9.5 have a ratio of Σ_1kpcin Hαrelative to their stellar continuum that is lower by (19 ± 2)% compared toz∼ 1 galaxies. Σ_1kpc,Hα/Σ_1kpc,Contdecreases toward higher stellar masses. The majority of the redshift evolution in Σ_1kpc,Hα/Σ_1kpc,Contversus stellar mass stems from the fact that log(Σ_1kpc,Hα) declines twice as much as log(Σ_1kpc,Cont) fromz∼ 1 to 0.5 (at a fixed stellar mass of log(M_*/M_⊙) = 9.5). By comparing our results to the TNG50 cosmological magneto-hydrodynamical simulation, we rule out dust as the driver of this evolution. Our results are consistent with inside-out quenching following in the wake of inside-out growth, the former of which drives the significant drop in Σ_1kpc,Hαfromz∼ 1 toz∼ 0.5.

    

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