The SCUBA-2 Cosmology Legacy Survey: 850um maps, catalogues and number counts
Monthly Notices of the Royal Astronomical Society Oxford University Press 465:2 (2016) 1789-1806
Authors:
JE Geach, JS Dunlop, M Halpern, I Smail, PVD Werf, DM Alexander, O Almaini, I Aretxaga, V Arumugam, V Asboth, M Banerji, J Beanlands, PN Best, AW Blain, M Birkinshaw, EL Chapin, SC Chapman, C-C Chen, A Chrysostomou, C Clarke, DL Clements, C Conselice, KEK Coppin, WI Cowley, ALR Danielson, S Eales, AC Edge, D Farrah, A Gibb, CM Harrison, NK Hine, D Hughes, RJ Ivison, Matthew Jarvis, T Jenness, SF Jones, A Karim, M Koprowski, KK Knudsen, CG Lacey, T Mackenzie, G Marsden, K McAlpine, R McMahon, R Meijerink, MJ Michalowski, SJ Oliver, MJ Page, JA Peacock, Dimitra Rigopoulou
Abstract:
We present a catalogue of ∼3,000 submillimetre sources detected (≥3.5σ) at 850μm over ∼5 deg2 surveyed as part of the James Clerk Maxwell Telescope (JCMT) SCUBA-2 Cosmology Legacy Survey (S2CLS). This is the largest survey of its kind at 850μm, increasing the sample size of 850-μm-selected submillimetre galaxies by an order of magnitude. The wide 850μm survey component of S2CLS covers the extragalactic fields: UKIDSS-UDS, COSMOS, Akari-NEP, Extended Groth Strip, Lockman Hole North, SSA22 and GOODS-North. The average 1σ depth of S2CLS is 1.2 mJy beam−1, approaching the SCUBA-2 850μm confusion limit, which we determine to be σc ≈ 0.8 mJy beam−1. We measure the 850μm number counts, reducing the Poisson errors on the differential counts to approximately 4% at S850 ≈ 3 mJy. With several independent fields, we investigate field-to-field variance, finding that the number counts on 0.5–1° scales are generally within 50% of the S2CLS mean for S850 > 3 mJy, with scatter consistent with the Poisson and estimated cosmic variance uncertainties, although there is a marginal (2σ) density enhancement in GOODS-North. The observed counts are in reasonable agreement with recent phenomenological and semi-analytic models, although determining the shape of the faint end slope (S850 < 3 mJy) remains a key test. The large solid angle of S2CLS allows us to measure the bright-end counts: at S850 > 10 mJy there are approximately ten sources per square degree, and we detect the distinctive up-turn in the number counts indicative of the detection of local sources of 850μm emission, and strongly lensed high-redshift galaxies. All calibrated maps and the catalogue are made publicly available.
