A3COSMOS: the dust attenuation of star-forming galaxies at z = 2.5–4.0 from the COSMOS-ALMA archive
ABSTRACT

We present an analysis of the dust attenuation of star-forming galaxies at z = 2.5–4.0 through the relationship between the UV spectral slope (β), stellar mass (M*), and the infrared excess (IRX = LIR/LUV) based on far-infrared continuum observations from the Atacama Large Millimeter/sub-millimeter Array (ALMA). Our study exploits the full ALMA archive over the COSMOS field processed by the A3COSMOS team, which includes an unprecedented sample of ∼1500 galaxies at z ∼ 3 as primary or secondary targets in ALMA band 6 or 7 observations with a median continuum sensitivity of 126 $\rm {\mu Jy\, beam}^{-1}$ (1σ). The detection rate is highly mass dependent, decreasing drastically below log (M*/M⊙) = 10.5. The detected galaxies show that the IRX–β relationship of massive (log M*/M⊙ > 10) main-sequence galaxies at z = 2.5–4.0 is consistent with that of local galaxies, while starbursts are generally offset by $\sim 0.5\, {\rm dex}$ to larger IRX values. At the low-mass end, we derive upper limits on the infrared luminosities through stacking of the ALMA data. The combined IRX–M* relation at $\rm {log\, ({\it M}_{\ast }/\mathrm{M}_{\odot })\gt 9}$ exhibits a significantly steeper slope than reported in previous studies at similar redshifts, implying little dust obscuration at log M*/M⊙ < 10. more »

Authors:
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Publication Date:
NSF-PAR ID:
10128010
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
491
Issue:
4
Page Range or eLocation-ID:
p. 4724-4734
ISSN:
0035-8711
Publisher:
Oxford University Press
1. ABSTRACT We report the serendipitous discovery of a dust-obscured galaxy observed as part of the Atacama Large Millimeter Array (ALMA) Large Program to INvestigate [C ii] at Early times (ALPINE). While this galaxy is detected both in line and continuum emissions in ALMA Band 7, it is completely dark in the observed optical/near-infrared bands and only shows a significant detection in the UltraVISTA Ks band. We discuss the nature of the observed ALMA line, that is [C ii] at $z$ ∼ 4.6 or high-J CO transitions at $z$ ∼ 2.2. In the first case, we find a [C ii]/FIR luminosity ratio of $\mathrm{log}{(L_{[\mathrm{more » 2. Abstract We present ALMA [C ii] line and far-infrared (FIR) continuum observations of three$z \gt 6$low-luminosity quasars ($M_{\rm 1450} \gt -25$mag) discovered by our Subaru Hyper Suprime-Cam (HSC) survey. The [C ii] line was detected in all three targets with luminosities of$(2.4\mbox{--}9.5) \times 10^8\, L_{\odot }$, about one order of magnitude smaller than optically luminous ($M_{\rm 1450} \lesssim -25$mag) quasars. The FIR continuum luminosities range from$\lt 9 \times 10^{10}\, L_{\odot }$(3$\sigma$limit) to${\sim } 2 \times 10^{12}\, L_{\odot }$, indicating a wide range in star formation rates in these galaxies. Most of the HSC quasars studiedmore » 3. ABSTRACT We present predictions for high redshift (z = 2−10) galaxy populations based on the IllustrisTNG simulation suite and a full Monte Carlo dust radiative transfer post-processing. Specifically, we discuss the H α and H β +$[\rm O \,{\small III}]$luminosity functions up to z = 8. The predicted H β +$[\rm O \,{\small III}]$luminosity functions are consistent with present observations at z ≲ 3 with${\lesssim} 0.1\, {\rm dex}$differences in luminosities. However, the predicted H α luminosity function is${\sim }0.3\, {\rm dex}\$ dimmer than the observed one at z ≃ 2. Furthermore, we explore continuum spectral indices, the Balmer break at 4000 Å; (D4000)more »