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An ALMA Survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS Field: Number Counts of Submillimeter Galaxies

Stach, Stuart M.; Smail, Ian; Swinbank, A.M.; Simpson, J.M.; Geach, J.E.; An, Fang Xia; Almaini, Omar; Arumugam, Vinodiran; Blain, A.W.; Chapman, S.C.; Chen, Chian-Chou; Conselice, C.J.; Cooke, E.A.; Coppin, K.E.K.; Dunlop, J.S.; Farrah, Duncan; Gullberg, B.; Hartley, W.; Ivison, R.J.; Maltby, D.T.; Michałowski, M.J.; Scott, Douglas; Simpson, Chris; Thomson, A.P.; Wardlow, J.L.; Werf, P. van der

An ALMA Survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS Field: Number Counts of Submillimeter Galaxies Thumbnail


Stuart M. Stach

J.M. Simpson

J.E. Geach

Fang Xia An

Omar Almaini

Vinodiran Arumugam

A.W. Blain

S.C. Chapman

Chian-Chou Chen

C.J. Conselice

E.A. Cooke

K.E.K. Coppin

J.S. Dunlop

Duncan Farrah

B. Gullberg

W. Hartley

R.J. Ivison

D.T. Maltby

M.J. Michałowski

Douglas Scott

Chris Simpson

A.P. Thomson

J.L. Wardlow

P. van der Werf


We report the first results of AS2UDS, an 870 μm continuum survey with the Atacama Large Millimeter/Submillimeter Array (ALMA) of a total area of ~50 arcmin2 comprising a complete sample of 716 submillimeter sources drawn from the SCUBA-2 Cosmology Legacy Survey (S2CLS) map of the UKIDSS/UDS field. The S2CLS parent sample covers a 0.96 degree2 field at σ 850 = 0.90 ± 0.05 mJy beam−1. Our deep, high-resolution ALMA observations with σ 870 ~ 0.25 mJy and a 0farcs15–0farcs30 FWHM synthesized beam, provide precise locations for 695 submillimeter galaxies (SMGs) responsible for the submillimeter emission corresponding to 606 sources in the low-resolution, single-dish map. We measure the number counts of SMGs brighter than S 870 ≥ 4 mJy, free from the effects of blending and show that the normalization of the counts falls by 28% ± 2% in comparison with the SCUBA-2 published counts, but that the shape remains unchanged. We determine that ${44}_{-14}^{+16}$% of the brighter single-dish sources with S 850 ≥ 9 mJy consist of a blend of two or more ALMA-detectable SMGs brighter than S 870 ~ 1 mJy (corresponding to a galaxy with a total-infrared luminosity of L IR gsim 1012 L ⊙), in comparison with 28% ± 2% for the single-dish sources at S 850 ≥ 5 mJy. Using the 46 single-dish submillimeter sources that contain two or more ALMA-detected SMGs with photometric redshifts, we show that there is a significant statistical excess of pairs of SMGs with similar redshifts (<1% probability of occurring by chance), suggesting that at least 30% of these blends arise from physically associated pairs of SMGs.

Journal Article Type Article
Acceptance Date May 15, 2018
Online Publication Date Jun 25, 2018
Publication Date Jun 25, 2018
Deposit Date Jul 12, 2018
Publicly Available Date Jul 12, 2018
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 860
Issue 2
Article Number 161
Public URL


Published Journal Article (1.1 Mb)

Copyright Statement
© 2018. The American Astronomical Society. All rights reserved.

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