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
0.″15-0.″30 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 ≳ 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 (
© 2018. The American Astronomical Society. All rights reserved.
Author was employed at another UK HEI at the time of submission and was deposited at Durham University Repository, see link http://dro.dur.ac.uk/25522/