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Published July 2017 | public
Journal Article

The SCUBA-2 Cosmology Legacy Survey: the nature of bright submm galaxies from 2 deg² of 850-μm imaging

Abstract

We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses (Mstar)] of bright (S850 ≥ 4 mJy) submm galaxies in the 2 deg2 COSMOS and UDS fields selected with SCUBA-2/JCMT. We complete the galaxy identification process for all (2000) S/N ≥ 3.5 850-µm sources, but focus our scientific analysis on a high-quality subsample of 651 S/N ≥ 4 sources with complete multiwavelength coverage including 1.1-mm imaging. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up of 29 sources in our sample. Considering >4 mJy ALMA sources, our identification method has a completeness of 86 per cent with a reliability of 92 per cent, and only 15–20 per cent of sources are significantly affected by multiplicity (when a secondary component contributes >1/3 of the primary source flux). The impact of source blending on the 850-µm source counts as determined with SCUBA-2 is modest; scaling the single-dish fluxes by 0.9 reproduces the ALMA source counts. For our final SCUBA- 2 sample, we find median z = 2.40+0.10 −0.04, SFR = 287 ± 6 M� yr−1 and log(Mstar/M�) = 11.12 ± 0.02 (the latter for 349/651 sources with optical identifications). These properties clearly locate bright submm galaxies on the high-mass end of the 'main sequence' of starforming galaxies out to z 6, suggesting that major mergers are not a dominant driver of the high-redshift submm-selected population. Their number densities are also consistent with the evolving galaxy stellar mass function. Hence, the submm galaxy population is as expected, albeit reproducing the evolution of the main sequence of star-forming galaxies remains a challenge for theoretical models/simulations. Key

Additional Information

© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. We thank Joanna Baradziej, Ian Smail, James Simpson, and our anonymous referee for comments and suggestions. MJM acknowledges the support of the UK Science and Technology Facilities Council (STFC), British Council Researcher Links Travel Grant and the hospitality at the Instituto Nacional de Astrofísica, Óptica y Electrónica. JSD acknowledges the support of the European Research Council via the award of an Advanced Grant, and the contribution of the EC FP7 SPACE project ASTRODEEP (ref. no: 312725). MPK acknowledges the STFC Studentship Enhancement Programme grant and the Carnegie Trust Research Incentive Grant (PI: Michałowski). The James Clerk Maxwell Telescope 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. Additional funds for the construction of SCUBA-2 were provided by the Canada Foundation for Innovation. This work is based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory as part of programme ID 179.A-2005, using data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. This study was based in part on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada–France–Hawaii Telescope (CFHT) that is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the CFHT Legacy Survey, a collaborative project of NRC and CNRS. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This research has made use of data from HerMES project (http://hermes.sussex.ac.uk/). HerMES is a Herschel Key Programme utilizing Guaranteed Time from the SPIRE instrument team, ESAC scientists and a mission scientist. The HerMES data were accessed through the Herschel Database in Marseille (HeDaM – http://hedam.lam.fr) operated by CeSAM and hosted by the Laboratoire d'Astrophysique de Marseille. PACS has been developed by a consortium of institutes led by MPE (Germany) and including UVIE (Austria); KU Leuven, CSL, IMEC (Belgium); CEA, LAM (France); MPIA (Germany); INAF-IFSI/OAA/OAP/OAT, LENS, SISSA (Italy); IAC (Spain). This development has been supported by the funding agencies BMVIT (Austria), ESA-PRODEX (Belgium), CEA/CNES (France), DLR (Germany), ASI/INAF (Italy) and CICYT/MCYT (Spain). SPIRE has been developed by a consortium of institutes led by Cardiff University (UK) and including Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, Univ. Sussex (UK) and Caltech, JPL, NHSC, Univ. Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC (UK) and NASA (USA). This work is based on observations taken by the 3D-HST Treasury Program (GO 12177 and 12328) with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Program 185.A-0791, and made available by the VUDS team at the CESAM data centre, Laboratoire d'Astrophysique de Marseille, France. The HST data matched to the VUDS-DR1 are described in Grogin et al. (2011) and Koekemoer et al. (2011) for CANDELS and include data from the ERS (Windhorst et al. 2011). This paper uses data from the VIMOS Public Extragalactic Redshift Survey (VIPERS). VIPERS has been performed using the ESO Very Large Telescope, under the 'Large Programme' 182.A-0886. The participating institutions and funding agencies are listed at http://vipers.inaf.it, based on zCOSMOS observations carried out using the Very Large Telescope at the ESO Paranal Observatory under Programme ID: LP175.A-0839. This research has made use of the Tool for OPerations on Catalogues And Tables (TOPCAT; Taylor 2005): www.starlink.ac.uk/topcat/; SAOImage DS9, developed by Smithsonian Astrophysical Observatory (Joye & Mandel 2003); SEXTRACTOR: Software for source extraction (Bertin & Arnouts 1996) and NASA's Astrophysics Data System Bibliographic Services.

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Created:
August 19, 2023
Modified:
October 26, 2023