An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS Field (AS2COSPEC): Physical Properties of z = 2–5 Ultra- and Hyperluminous Infrared Galaxies

Cheng-Lin Liao*, Chian-Chou Chen*, Wei-Hao Wang, Ian Smail, Y. Ao, S. C. Chapman, U. Dudzevičiūtė, M. Frias Castillo, Minju M. Lee, Stephen Serjeant, A. M. Swinbank, Dominic J. Taylor, Hideki Umehata, Y. Zhao

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

6 Downloads (Pure)

Abstract

We report the physical properties of the 18 brightest (S870 μm = 12.4–19.2 mJy) and not strongly lensed 870 μm–selected dusty star-forming galaxies (DSFGs), also known as submillimeter galaxies (SMGs), in the COSMOS field. This sample is part of an ALMA band 3 spectroscopic survey (AS2COSPEC), and spectroscopic redshifts are measured in 17 of them at z = 2–5. We perform spectral energy distribution analyses and deduce a median total infrared luminosity of LIR = (1.3 ± 0.1) × 1013L, infrared-based star formation rate (SFR) of SFRIR = 1390 ± 150 M yr−1, stellar mass of M* = (1.4 ± 0.6) × 1011M, dust mass of Mdust = (3.7 ± 0.5) × 109M, and molecular gas mass of Mgas = (αCO/0.8)(1.2 ± 0.1) × 1011M, suggesting that they are one of the most massive, ISM-enriched, and actively star-forming systems at z = 2–5. In addition, compared to less massive and less active galaxies at similar epochs, SMGs have comparable gas fractions; however, they have a much shorter depletion time, possibly caused by more active dynamical interactions. We determine a median dust emissivity index of β = 2.1 ± 0.1 for our sample, and by combining our results with those from other DSFG samples, we find no correlation of β with redshift or infrared luminosity, indicating similar dust grain compositions across cosmic time for infrared luminous galaxies. We also find that AS2COSPEC SMGs have one of the highest dust-to-stellar mass ratios, with a median of 0.02 ± 0.01, significantly higher than model predictions, possibly due to too-strong active galactic nucleus feedback implemented in the model. Finally, our complete and uniform survey enables us to put constraints on the most massive end of the dust and molecular gas mass functions.
Original languageEnglish
Article number226
JournalAstrophysical Journal
Volume961
Issue number2
Number of pages25
ISSN0004-637X
DOIs
Publication statusPublished - 2024

Keywords

  • Galaxy evolution
  • Galaxy formation
  • Infrared galaxies
  • Interstellar line emission
  • Interstellar medium
  • Submillimeter astronomy

Fingerprint

Dive into the research topics of 'An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS Field (AS2COSPEC): Physical Properties of z = 2–5 Ultra- and Hyperluminous Infrared Galaxies'. Together they form a unique fingerprint.

Cite this