University of Hertfordshire

From the same journal

From the same journal

By the same authors


  • S. M. Stach
  • I. Smail
  • A. M. Swinbank
  • F. X. An
  • O. Almaini
  • V. Arumugam
  • A. W. Blain
  • S. C. Chapman
  • C. J. Conselice
  • E. A. Cooke
  • J. S. Dunlop
  • D. Farrah
  • B. Gullberg
  • W. Hartley
  • R. J. Ivison
  • D. T. Maltby
  • M. J. Michałowski
  • D. Scott
  • J. L. Wardlow
  • P. van der Werf
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Original languageEnglish
Article number161
JournalThe Astrophysical Journal
Publication statusPublished - 25 Jun 2018


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 arcmin 2 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 degree 2 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 % 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 10 12 L o), 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.


11 pages, 4 figures, fixed typo (sorry Rob)

ID: 16085980