University of Hertfordshire

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  • staa1345

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  • Ian Smail
  • U. Dudzeviciute
  • Y. Matsuda
  • B. -C. Hsieh
  • A. M. Swinbank
  • S. M. Stach
  • Fang Xia An
  • J. E. Birkin
  • Y. Ao
  • A. J. Bunker
  • S. C. Chapman
  • Chian-Chou Chen
  • K. E. K. Coppin
  • S. Ikarashi
  • R. J. Ivison
  • I. Mitsuhashi
  • T. Saito
  • H. Umehata
  • R. Wang
  • Y. Zhao
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Original languageEnglish
Article numberstaa1345
Pages (from-to)3409–3430
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Volume495
Issue3
Early online date18 May 2020
DOIs
Publication statusPublished - 1 Jul 2020

Abstract

We present an ALMA study of the ~180 brightest sources in the SCUBA-2 map of the COSMOS field from the S2COSMOS survey, as a pilot study for AS2COSMOS - a full survey of the ~1,000 sources in this field. In this pilot we have obtained 870-um continuum maps of an essentially complete sample of the brightest 182 sub-millimetre sources (S_850um=6.2mJy) in COSMOS. Our ALMA maps detect 260 sub-millimetre galaxies (SMGs) spanning a range in flux density of S_870um=0.7-19.2mJy. We detect more than one SMG counterpart in 34+/-2 per cent of sub-millimetre sources, increasing to 53+/-8 per cent for SCUBA-2 sources brighter than S_850um>12mJy. We estimate that approximately one-third of these SMG-SMG pairs are physically associated (with a higher rate for the brighter secondary SMGs, S_870um>3mJy), and illustrate this with the serendipitous detection of bright [CII] 157.74um line emission in two SMGs, AS2COS0001.1 & 0001.2 at z=4.63, associated with the highest significance single-dish source. Using our source catalogue we construct the interferometric 870um number counts at S_870um>6.2mJy. We use the extensive archival data of this field to construct the multiwavelength spectral energy distribution of each AS2COSMOS SMG, and subsequently model this emission with MAGPHYS to estimate their photometric redshifts. We find a median photometric redshift for the S_870um>6.2mJy AS2COSMOS sample of z=2.87+/-0.08, and clear evidence for an increase in the median redshift with 870-um flux density suggesting strong evolution in the bright-end of the 870um luminosity function.

Notes

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 495, Issue 3, July 2020, Pages 3409–3430 ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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