We present a search for extremely red, dust-obscured,
This content will become publicly available on July 1, 2024
We present morphologies of galaxies at
- Award ID(s):
- 1835213
- NSF-PAR ID:
- 10480076
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 951
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 72
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract z > 7 galaxies with JWST/NIRCam+MIRI imaging over the first 20 arcmin2of publicly available Cycle 1 data from the COSMOS-Web, CEERS, and PRIMER surveys. Based on their red color in F277W−F444W (∼2.5 mag) and detection in MIRI/F770W (∼25 mag), we identify two galaxies, COS-z8M1 and CEERS-z7M1, that have best-fit photometric redshifts of and , respectively. We perform spectral energy distribution fitting with a variety of codes (includingbagpipes ,prospector ,beagle , andcigale ) and find a >95% probability that these indeed lie atz > 7. Both sources are compact (R eff≲ 200 pc) and highly obscured (A V ∼ 1.5–2.5) and, at our best-fit redshift estimates, likely have strong [Oiii ]+Hβ emission contributing to their 4.4μ m photometry. We estimate stellar masses of ∼1010M ⊙for both sources; by virtue of detection in MIRI at 7.7μ m, these measurements are robust to the inclusion of bright emission lines, for example, from an active galactic nucleus. We identify a marginal (2.9σ ) Atacama Large Millimeter/submillimeter Array detection at 2 mm within 0.″5 of COS-z8M1, which, if real, would suggest a remarkably high IR luminosity of ∼1012L ⊙. These two galaxies, if confirmed atz ∼ 8, would be extreme in their stellar and dust masses and may be representative of a substantial population of highly dust-obscured galaxies at cosmic dawn. -
Abstract We present a measurement of the intrinsic space density of intermediate-redshift (
z ∼ 0.5), massive (M *∼ 1011M ⊙), compact (R e ∼ 100 pc) starburst (ΣSFR∼ 1000M ⊙yr−1kpc−1) galaxies with tidal features indicative of them having undergone recent major mergers. A subset of them host kiloparsec-scale, > 1000 km s−1outflows and have little indication of AGN activity, suggesting that extreme star formation can be a primary driver of large-scale feedback. The aim for this paper is to calculate their space density so we can place them in a better cosmological context. We do this by empirically modeling the stellar populations of massive, compact starburst galaxies. We determine the average timescale on which galaxies that have recently undergone an extreme nuclear starburst would be targeted and included in our spectroscopically selected sample. We find that massive, compact starburst galaxies targeted by our criteria would be selectable for Myr and have an intrinsic space density . This space density is broadly consistent with ourz ∼ 0.5 compact starbursts being the most extremely compact and star-forming low-redshift analogs of the compact star-forming galaxies in the early universe, as well as them being the progenitors to a fraction of intermediate-redshift, post-starburst, and compact quiescent galaxies. -
Abstract 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 and a median star formation rate of . We measure the faint electron-temperature-sensitive [Oiii ]λ 4363 emission line at 2.5σ (4.1σ ) significance when considering a bootstrapped (statistical-only) uncertainty spectrum. This yields a direct-method oxygen abundance of ( ). We investigate the applicability at highz 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 fixedM *, our composite is well represented by thez ∼ 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 , we find excellent agreement with the FIRE MZR. Our composite is consistent with no metallicity evolution, at fixedM *and SFR, of the locally defined fundamental metallicity relation. We measure the doublet ratio [Oii ]λ 3729/[Oii ]λ 3726 = 1.56 ± 0.32 (1.51 ± 0.12) and a corresponding electron density of ( ) when considering the bootstrapped (statistical-only) error spectrum. This result suggests that lower-mass galaxies have lower densities than higher-mass galaxies atz ∼ 2. -
Abstract We present measurements of the rest-frame UV spectral slope,
β , for a sample of 36 faint star-forming galaxies atz ∼ 9–16 discovered in one of the deepest JWST NIRCam surveys to date, the Next Generation Deep Extragalactic Exploratory Public Survey. We use robust photometric measurements for UV-faint galaxies (down toM UV∼ −16), originally published in Leung et al., and measure values of the UV spectral slope via photometric power-law fitting to both the observed photometry and stellar population models obtained through spectral energy distribution (SED) fitting withBagpipes . We obtain a median and 68% confidence interval forβ from photometric power-law fitting of and from SED fitting, for the full sample. We show that when only two to three photometric detections are available, SED fitting has a lower scatter and reduced biases than photometric power-law fitting. We quantify this bias and find that after correction the median . We measure physical properties for our galaxies withBagpipes and find that our faint ( ) sample is low in mass ( ), fairly dust-poor ( mag), and modestly young ( yr) with a median star formation rate of . We find no strong evidence for ultrablue UV spectral slopes (β ∼ −3) within our sample, as would be expected for exotically metal-poor (Z /Z ⊙< 10−3) stellar populations with very high Lyman continuum escape fractions. Our observations are consistent with model predictions that galaxies of these stellar masses atz ∼ 9–16 should have only modestly low metallicities (Z /Z ⊙∼ 0.1–0.2). -
Abstract The bimodal absorption system imaging campaign (BASIC) aims to characterize the galaxy environments of a sample of 36 H
i -selected partial Lyman limit systems (pLLSs) and Lyman limit systems (LLSs) in 23 QSO fields atz ≲ 1. These pLLSs/LLSs provide a unique sample of absorbers with unbiased and well-constrained metallicities, allowing us to explore the origins of metal-rich and low-metallicity circumgalactic medium (CGM) atz < 1. Here we present Keck/KCWI and Very Large Telescope/MUSE observations of 11 of these QSO fields (19 pLLSs) that we combine with Hubble Space Telescope/Advanced Camera for Surveys imaging to identify and characterize the absorber-associated galaxies at 0.16 ≲z ≲ 0.84. We find 23 unique absorber-associated galaxies, with an average of one associated galaxy per absorber. For seven absorbers, all with <10% solar metallicities, we find no associated galaxies with withinρ /R virand ∣Δv ∣/v esc≤ 1.5 with respect to the absorber. We do not find any strong correlations between the metallicities or Hi column densities of the gas and most of the galaxy properties, except for the stellar mass of the galaxies: the low-metallicity ([X/H] ≤ −1.4) systems have a probability of for having a host galaxy with withinρ /R vir≤ 1.5, while the higher metallicity absorbers have a probability of . This implies metal-enriched pLLSs/LLSs atz < 1 are typically associated with the CGM of galaxies with , whereas low-metallicity pLLSs/LLSs are found in more diverse locations, with one population arising in the CGM of galaxies and another more broadly distributed in overdense regions of the universe. Using absorbers not associated with galaxies, we estimate the unweighted geometric mean metallicity of the intergalactic medium to be [X/H] ≲ −2.1 atz < 1, which is lower than previously estimated.