University of Hertfordshire

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From the same journal

By the same authors

An ALMA survey of the brightest sub-millimetre sources in the SCUBA-2 COSMOS field

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  • staa1345

    Final published version, 10.2 MB, PDF document

  • James Simpson
  • 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
  • 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
Early online date18 May 2020
Publication statusPublished - 1 Jul 2020


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.


Funding Information: We thank the Referee and Editor for comments that have improved the clarity and presentation of this work. The Durham co-authors acknowledge support from STFC (ST/P000541/1 and ST/T000244/1) and JMS gratefully acknowledges support from the EACOA fellowship programme. UD and JEB acknowledge the support of STFC studentships (ST/R504725/1 and ST/S50536/1, respectively). YM acknowledges JSPS KAKENHI grant nos. 25287043, 17H04831, and 17KK0098. WHW acknowledges grant support from the Ministry of Science and Technology of Taiwan (105-2112-M-001-029-MY3 and 108-2112-M-001-014-MY3). YA acknowledges financial support through NSFC grant 11933011. KEKC acknowledges support from STFC (ST/R000905/1) and a Royal Society/Leverhulme Trust Senior Fellowship (SRF/R1/191013). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.00463.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. This analysis used data from the S2COSMOS survey (M16AL002) on the JCMT, which in turn included data from S2CLS (MJLSC02) and the JCMT archive. The JCMT is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan; Academia Sinica Institute of Astronomy and Astrophysics; the Korea Astronomy and Space Science Institute; the Operation, Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments, budgeted from the Ministry of Finance (MOF) of China and administrated by the Chinese Academy of Sciences (CAS); and the National Key R&D Program of China (No. 2017YFA0402700). Additional funding support is provided by the Science and Technology Facilities Council of the United Kingdom and participating universities in the United Kingdom and Canada (ST/M007634/1, ST/M003019/1, and ST/N005856/1). The JCMT has historically been operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the United Kingdom, the National Research Council of Canada, and the Netherlands Organization for Scientific Research and data from observations undertaken during this period of operation are used in this manuscript. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency. Publisher Copyright: © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.

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