University of Hertfordshire

By the same authors


  • FangXia An
  • J. M. Simpson
  • Ian Smail
  • A. M. Swinbank
  • Cong Ma
  • Daizhong Liu
  • P. Lang
  • E. Schinnerer
  • A. Karim
  • B. Magnelli
  • S. Leslie
  • F. Bertoldi
  • Chian-Chou Chen
  • Y. Matsuda
  • S. M. Stach
  • J. L. Wardlow
  • B. Gullberg
  • R. J. Ivison
  • Y. Ao
  • R. T. Coogan
  • A. P. Thomson
  • S. C. Chapman
  • R. Wang
  • Wei-Hao Wang
  • Y. Yang
  • R. Asquith
  • N. Bourne
  • N. K. Hine
  • L. C. Ho
  • H. S. Hwang
  • Y. Kato
  • K. Lacaille
  • A. J. R. Lewis
  • I. Oteo
  • J. Scholtz
  • M. Sawicki
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Original languageEnglish
Article number48
Number of pages18
JournalThe Astrophysical Journal, Volume
Early online date19 Nov 2019
Publication statusPublished - 20 Nov 2019


We identify multi-wavelength counterparts to 1,147 submillimeter sources from the S2COSMOS SCUBA-2 survey of the COSMOS field by employing a recently developed radio$+$machine-learning method trained on a large sample of ALMA-identified submillimeter galaxies (SMGs), including 260 SMGs identified in the AS2COSMOS pilot survey. In total, we identify 1,222 optical/near-infrared(NIR)/radio counterparts to the 897 S2COSMOS submillimeter sources with S$_{850}$>1.6mJy, yielding an overall identification rate of ($78\pm9$)%. We find that ($22\pm5$)% of S2COSMOS sources have multiple identified counterparts. We estimate that roughly 27% of these multiple counterparts within the same SCUBA-2 error circles very likely arise from physically associated galaxies rather than line-of-sight projections by chance. The photometric redshift of our radio$+$machine-learning identified SMGs ranges from z=0.2 to 5.7 and peaks at $z=2.3\pm0.1$. The AGN fraction of our sample is ($19\pm4$)%, which is consistent with that of ALMA SMGs in the literature. Comparing with radio/NIR-detected field galaxy population in the COSMOS field, our radio+machine-learning identified counterparts of SMGs have the highest star-formation rates and stellar masses. These characteristics suggest that our identified counterparts of S2COSMOS sources are a representative sample of SMGs at z


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