Casey, Caitlin M. and Chen, Chian-Chou and Cowie, Lennox L. and Barger, Amy J. and Capak, Peter and Ilbert, Olivier and Koss, Michael and Lee, Nicholas and Le Floc'h, Emeric and Sanders, David B. and Williams, Jonathan P. (2013) Characterization of SCUBA-2 450μm and 850μm selected galaxies in the COSMOS field. Monthly Notices of the Royal Astronomical Society, 436 (3). pp. 1919-1954. ISSN 0035-8711. http://resolver.caltech.edu/CaltechAUTHORS:20140204-071134082
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We present deep 450 μm and 850 μm observations of a large, uniformly covered 394 arcmin2 area in the Cosmic Evolution Survey (COSMOS) field obtained with the Scuba-2 instrument on the James Clerk Maxwell Telescope (JCMT). We achieve root-mean-square noise values of σ_(450) = 4.13 mJy and σ_(850) = 0.80 mJy. The differential and cumulative number counts are presented and compared to similar previous works. Individual point sources are identified at >3.6σ significance, a threshold corresponding to a 3–5 per cent sample contamination rate. We identify 78 sources at 450 μm and 99 at 850 μm, with flux densities S_(450) = 13–37 mJy and S_(850) = 2–16 mJy. Only 62–76 per cent of 450 μm sources are 850 μm detected and 61–81 per cent of 850 μm sources are 450 μm detected. The positional uncertainties at 450 μm are small (1–2.5 arcsec) and therefore allow a precise identification of multiwavelength counterparts without reliance on detection at 24 μm or radio wavelengths; we find that only 44 per cent of 450 μm sources and 60 per cent of 850 μm sources have 24 μm or radio counterparts. 450 μm selected galaxies peak at 〈z〉 = 1.95 ± 0.19 and 850 μm selected galaxies peak at 〈z〉 = 2.16 ± 0.11. The two samples occupy similar parameter space in redshift and luminosity, while their median SED peak wavelengths differ by ∼20–50 μm (translating to ΔT_(dust) = 8–12 K, where 450 μm selected galaxies are warmer). The similarities of the 450 μm and 850 μm populations, yet lack of direct overlap between them, suggests that submillimetre surveys conducted at any single far-infrared wavelength will be significantly incomplete (≳30 per cent) at censusing infrared-luminous star formation at high z.
|Additional Information:||© 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 September 4. Received 2013 August 5; in original form 2013 February 11. First published online: October 22, 2013. We would like to thank the referee for a very thoughtful and helpful report in reviewing this manuscript. CMC is generously supported by a Hubble Fellowship from Space Telescope Science Institute, grant HST-HF-51268.01-A. CCC and LC are generously supported by NSF grant AST 0709356. AB thanks the University of Wisconsin Research Committee with funds granted by the Wisconsin Alumni Research Foundation, and the David and Lucile Packard Foundation. CMC and DBS would like to thank the Aspen Center for Physics and the NSF grant 1066293 for many fruitful conversations with the community regarding this work during ‘The Obscured Universe’ summer workshop. The JCMT is 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 (until 2013 March 31) the Netherlands Organization for Scientific Research. Additional funds for the construction of SCUBA-2 were provided by the Canada Foundation for Innovation. The authors also wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.|
|Subject Keywords:||galaxies: evolution galaxies: high-redshift galaxies: starbursts infrared: galaxies|
|Official Citation:||Caitlin M. Casey, Chian-Chou Chen, Lennox L. Cowie, Amy J. Barger, Peter Capak, Olivier Ilbert, Michael Koss, Nicholas Lee, Emeric Le Floc'h, David B. Sanders, and Jonathan P. Williams Characterization of Scuba-2 450 μm and 850 μm selected galaxies in the COSMOS field MNRAS (December 11, 2013) Vol. 436 1919-1954 first published online October 22, 2013 doi:10.1093/mnras/stt1673|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||04 Feb 2014 16:02|
|Last Modified:||06 Jul 2015 17:35|
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