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Durham University

Department of Physics

Staff profile

Publication details for Professor Ian Smail

Hill, Ryley, Chapman, Scott C, Scott, Douglas, Petitpas, Glen, Smail, Ian, Chapin, Edward L, Gurwell, Mark A, Perry, Ryan, Blain, Andrew W, Bremer, Malcolm N, Chen, Chian-Chou, Dunlop, James S, Farrah, Duncan, Fazio, Giovanni G, Geach, James E, Howson, Paul, Ivison, R J, Lacaille, Kevin, Michałowski, Michał J, Simpson, James M, Swinbank, A M, van der Werf, Paul P & Wilner, David J (2018). High-resolution SMA imaging of bright submillimetre sources from the SCUBA-2 Cosmology Legacy Survey. Monthly Notices of the Royal Astronomical Society 477(2): 2042-2067.

Author(s) from Durham


We have used the Submillimeter Array (SMA) at 860 µm to observe the brightest sources in
the Submillimeter Common User Bolometer Array-2 (SCUBA-2) Cosmology Legacy Survey
(S2CLS). The goal of this survey is to exploit the large field of the S2CLS along with the
resolution and sensitivity of the SMA to construct a large sample of these rare sources and to
study their statistical properties. We have targeted 70 of the brightest single-dish SCUBA-2
850 µm sources down to S850 ≈ 8 mJy, achieving an average synthesized beam of 2.4 arcsec
and an average rms of σ860 = 1.5 mJy beam−1 in our primary beam-corrected maps. We
searched our SMA maps for 4σ peaks, corresponding to S860 6 mJy sources, and detected
62, galaxies, including three pairs. We include in our study 35 archival observations, bringing
our sample size to 105 bright single-dish submillimetre sources with interferometric followup.
We compute the cumulative and differential number counts, finding them to overlap with
previous single-dish survey number counts within the uncertainties, although our cumulative
number count is systematically lower than the parent S2CLS cumulative number count by
14 ± 6 per cent between 11 and 15 mJy. We estimate the probability that a 10 mJy singledish
submillimetre source resolves into two or more galaxies with similar flux densities to
be less than 15 per cent. Assuming the remaining 85 per cent of the targets are ultraluminous
starburst galaxies between z = 2 and 3, we find a likely volume density of 400 M yr−1
sources to be ∼ 3+0.7 −0.6 × 10−7 Mpc−3. We show that the descendants of these galaxies could be
4 × 1011 M local quiescent galaxies, and that about 10 per cent of their total stellar mass
would have formed during these short bursts of star formation.