The ALMA Spectroscopic Survey Large Program: The Infrared Excess of z = 1.5-10 UV-selected Galaxies and the Implied High-redshift Star Formation History

Journal
Date Issued
2020
Author(s)
Bouwens, Rychard
•
González-López, Jorge
•
Aravena, Manuel
•
•
Novak, Mladen
•
Stefanon, Mauro
•
Walter, Fabian
•
Boogaard, Leindert
•
Carilli, Chris
•
Dudzevičiūtė, Ugnė
•
Smail, Ian
•
Daddi, Emanuele
•
da Cunha, Elisabete
•
Ivison, Rob
•
Nanayakkara, Themiya
•
Cortes, Paulo
•
Cox, Pierre
•
Inami, Hanae
•
Oesch, Pascal
•
Popping, Gergö
•
Riechers, Dominik
•
van der Werf, Paul
•
Weiss, Axel
•
Fudamoto, Yoshi
•
Wagg, Jeff
DOI
Abstract
We make use of sensitive (9.3 μJy beam-1 rms) 1.2 mm continuum observations from the Atacama Large Millimeter/submillimeter Array (ALMA) Spectroscopic Survey in the Hubble Ultra-Deep Field (ASPECS) large program to probe dust-enshrouded star formation from 1362 Lyman-break galaxies spanning the redshift range z = 1.5-10 (to ˜7-28 M⊙ yr-1 at 4σ over the entire range). We find that the fraction of ALMA-detected galaxies in our z = 1.5-10 samples increases steeply with stellar mass, with the detection fraction rising from 0% at 109.0 M⊙ to ${85}_{-18}^{+9}$ % at >1010 M⊙. Moreover, on stacking all 1253 low-mass (<109.25 M⊙) galaxies over the ASPECS footprint, we find a mean continuum flux of -0.1 ± 0.4 μJy beam-1, implying a hard upper limit on the obscured star formation rate of <0.6 M⊙ yr-1 (4σ) in a typical low-mass galaxy. The correlation between the infrared excess (IRX) of UV-selected galaxies (LIR/LUV) and the UV-continuum slope is also seen in our ASPECS data and shows consistency with a Calzetti-like relation at > ${10}^{9.5}\,{M}_{\odot }$ and an SMC-like relation at lower masses. Using stellar mass and β measurements for z ˜ 2 galaxies over the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, we derive a new empirical relation between β and stellar mass and then use this correlation to show that our IRX-β and IRX-stellar mass relations are consistent with each other. We then use these constraints to express the IRX as a bivariate function of β and stellar mass. Finally, we present updated estimates of star formation rate density determinations at z > 3, leveraging present improvements in the measured IRX and recent probes of ultraluminous far-IR galaxies at z > 2.
Volume
902
Issue
2
Start page
112
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2020ApJ...902..112B
Rights
open.access
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