An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: Source catalogue and properties

Stach, Stuart M; Dudzevičiūtė, U; Smail, Ian; Swinbank, AM; Geach, JE; Simpson, JM; An, Fang Xia; Almaini, Omar; Arumugam, Vinodiran; Blain, AW; Chapman, SC; Chen, Chian-Chou; Conselice, CJ; Cooke, EA; Coppin, KEK; da Cunha, E; Dunlop, JS; Farrah, Duncan; Gullberg, B; Hodge, JA; Ivison, R; Kocevski, Dale D; Michałowski, MJ; Miyaji, Takamitsu; Scott, Douglas; Thomson, AP; Wardlow, JL; Weiss, Axel; Werf, P van der

Abstract

We present the catalogue and basic properties of sources in AS2UDS, an 870-μm continuum survey with the Atacama Large Millimetre/sub-millimetre Array (ALMA) of 716 single-dish sub-millimetre sources detected in the UKIDSS/UDS field by the SCUBA-2 Cosmology Legacy Survey. In our sensitive ALMA follow-up observations we detect 708 sub-millimetre galaxies (SMGs) at > 4.3σ significance across the ∼ 1-degree diameter field. We combine our precise ALMA positions with the extensive multi-wavelength coverage in the UDS field which yields spectral energy distributions for our SMGs and a median redshift of zphot = 2.61±0.09. This large sample reveals a statistically significant trend of increasing sub-millimetre flux with redshift suggestive of galaxy downsizing. 101 ALMA maps do not show a > 4.3σ SMG, but we demonstrate from stacking Herschel SPIRE observations at these positions, that the vast majority of these blank maps correspond to real single-dish sub-millimetre sources. We further show that these blank maps contain an excess of galaxies at zphot = 1.5–4 compared to random fields, similar to the redshift range of the ALMA-detected SMGs. In addition, we combine X-ray and mid-infrared active galaxy nuclei activity (AGN) indicators to yield a likely range for the AGN fraction of 8–28 % in our sample. Finally, we compare the redshifts of this population of high-redshift, strongly star-forming galaxies with the inferred formation redshifts of massive, passive galaxies being found out to z ∼ 2, finding reasonable agreement – in support of an evolutionary connection between these two classes of massive galaxy.

Citation

Stach, S. M., Dudzevičiūtė, U., Smail, I., Swinbank, A., Geach, J., Simpson, J., …Werf, P. V. D. (2019). An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: Source catalogue and properties. Monthly Notices of the Royal Astronomical Society, 487(4), 4648-4668. https://doi.org/10.1093/mnras/stz1536

• Journal Article Type: Article
• Acceptance Date: May 28, 2019
• Online Publication Date: Jun 6, 2019
• Publication Date: Aug 31, 2019
• Deposit Date: Jun 6, 2019
• Publicly Available Date: Jun 6, 2019
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 487
• Issue: 4
• Pages: 4648-4668
• DOI: https://doi.org/10.1093/mnras/stz1536