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

Rychard Bouwens, Jorge González-López, Manuel Aravena, Roberto Decarli, Mladen Novak, Mauro Stefanon, Fabian Walter, Leindert Boogaard, Chris Carilli, Ugne Dudzevičiūtė, Ian Smail, Emanuele Daddi, Elisabete Da Cunha, Rob Ivison, Themiya Nanayakkara, Paulo Cortes, Pierre Cox, Hanae Inami, Pascal Oesch, Gergö PoppingDominik Riechers, Paul Van Der Werf, Axel Weiss, Yoshi Fudamoto, Jeff Wagg

Research output: Contribution to journalReview articlepeer-review

12 Citations (Scopus)

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 o˙ 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 o˙ to 85-18+9% at >1010 M o˙. Moreover, on stacking all 1253 low-mass (<109.25 M o˙) 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 o˙ yr-1 (4σ) in a typical low-mass galaxy. The correlation between the infrared excess (IRX) of UV-selected galaxies (L IR/L UV) and the UV-continuum slope is also seen in our ASPECS data and shows consistency with a Calzetti-like relation at > 109.5Ṁ 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.

Original languageEnglish
Article number112
JournalAstrophysical Journal
Volume902
Issue number2
DOIs
Publication statusPublished - 2020 Oct 20
Externally publishedYes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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