Herschel-ATLAS: Properties of dusty massive galaxies at low and high redshifts

Abstract

We present a comparison of the physical properties of a rest-frame $250\hat{I}¼$m selected sample of massive, dusty galaxies from $0<z<5.3$. Our sample comprises 29 high-redshift submillimetre galaxies (SMGs) from the literature, and 843 dusty galaxies at $z<0.5$ from the Herschel-ATLAS, selected to have a similar stellar mass to the SMGs. The $z>1$ SMGs have an average SFR of $390_{-70}^{+80}$M${}_{\odot }$yr${}^{-1}$ which is 120 times that of the low-redshift sample matched in stellar mass to the SMGs (SFR$=3.3\pm 0.2$ M${}_{\odot }$yr${}^{-1}$). The SMGs harbour a substantial mass of dust ($1.2_{-0.2}^{+0.3}\times {10}^9$M${}_{\odot }$), compared to $(1.6\pm 0.1)\times {10}^8$M${}_{\odot }$ for low-redshift dusty galaxies. At low redshifts the dust luminosity is dominated by the diffuse ISM, whereas a large fraction of the dust luminosity in SMGs originates from star-forming regions. At the same dust mass SMGs are offset towards a higher SFR compared to the low-redshift H-ATLAS galaxies. This is not only due to the higher gas fraction in SMGs but also because they are undergoing a more efficient mode of star formation, which is consistent with their bursty star-formation histories. The offset in SFR between SMGs and low-redshift galaxies is similar to that found in CO studies, suggesting that dust mass is as good a tracer of molecular gas as CO.

17 pages, 8 pages in Appendix, 12 figures, 2 tables. Accepted for publication in MNRAS. Minor typos corrected to match published version