An ALMA survey of the SCUBA-2 CLS UDS field: Physical properties of 707 Sub-millimetre Galaxies

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 similar to 1 deg(2) field, including similar to 17 per cent, which are undetected at K greater than or similar to 25.7 mag. We interpret their ultraviolet-to-radio data using MAGPHYS and determine a median redshift of z = 2.61 +/- 0.08 (1 sigma range of z = 1.8-3.4) with just similar to 6 per cent at z greater than or similar to 4. Our survey provides a sample of massive dusty galaxies at z > 1, with median dust and stellar masses of M-d = (6.8 +/- 0.3) x 10(8) M-circle dot (thus, gas masses of similar to 10(11) M-circle dot) and M* = (1.26 +/- 0.05) x 10(11) M-circle dot. We find no evolution in dust temperature at a constant far-infrared luminosity across z similar to 1.5-4. The gas mass function of our sample increases to z similar to 2-3 and then declines at z > 3. The space density and masses of SMGs suggest that almost all galaxies with M* greater than or similar to 3 x 10(11) M-circle dot, 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 M-h similar to 6 x 10(12) M-circle dot, 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.