An ALMA survey of the SCUBA-2 CLS UDS field: physical properties of 707 sub-millimetre galaxies
Thomson, A. P.; Ivison, R. J.; Scott, D.; Smail, Ian; Dunlop, J. S.; Farrah, D.; Weiss, A.; Walter, F.; An, Fang Xia; Swinbank, A. M.; Wardlow, J. L.; van der Werf, P.; Arumugam, V.; da Cunha, E.; Hodge, J. A.; Simpson, J. M.; Hartley, W. G.; Conselice, C. J.; Blain, A. W.; Geach, J. E.; Chapman, S. C.; Gullberg, B.; Chen, C. -C.; Almaini, O.; Coppin, K. E. K.; Simpson, C. J.; Dudzevičiūtė, U.; Stach, S. M.; Maltby, D. T.; Birkin, J.
United Kingdom, Australia, South Africa, France, Canada, Germany, United States, Netherlands
Abstract
We analyse the physical properties of a large, homogeneously selected sample of ALMA-located sub-millimetre galaxies (SMGs). This survey, AS2UDS, identified 707 SMGs across the ∼1 deg2 field, including ∼17 per cent, which are undetected at K ≳ 25.7 mag. We interpret their ultraviolet-to-radio data using magphys and determine a median redshift of z = 2.61 ± 0.08 (1σ range of z = 1.8-3.4) with just ∼6 per cent at z > 4. Our survey provides a sample of massive dusty galaxies at z ≳ 1, with median dust and stellar masses of Md = (6.8 ± 0.3) × 108 M⊙ (thus, gas masses of ∼1011 M⊙) and M* = (1.26 ± 0.05) × 1011 M⊙. We find no evolution in dust temperature at a constant far-infrared luminosity across z ∼ 1.5-4. The gas mass function of our sample increases to z ∼ 2-3 and then declines at z > 3. The space density and masses of SMGs suggest that almost all galaxies with M* ≳ 3 × 1011 M⊙ have passed through an SMG-like phase. The redshift distribution is well fit by a model combining evolution of the gas fraction in haloes with the growth of halo mass past a critical threshold of Mh ∼ 6 × 1012 M⊙, thus SMGs may represent the highly efficient collapse of gas-rich massive haloes. We show that SMGs are broadly consistent with simple homologous systems in the far-infrared, consistent with a centrally illuminated starburst. Our study provides strong support for an evolutionary link between the active, gas-rich SMG population at z > 1 and the formation of massive, bulge-dominated galaxies across the history of the Universe.