Herschel-ATLAS: properties of dusty massive galaxies at low and high redshifts
Smail, I.; Ivison, R. J.; Ibar, E.; Aragón-Salamanca, A.; Dunne, L.; Dye, S.; Eales, S.; Maddox, S.; Valiante, E.; Smith, M. W. L.; Gomez, H. L.; da Cunha, E.; Bourne, N.; Rowlands, K.; Smith, D. J. B.; Clark, C. J. R.; Alpaslan, M.; Driver, S.; Robotham, A.
United Kingdom, New Zealand, Germany, Australia, Chile
Abstract
We present a comparison of the physical properties of a rest-frame 250-μm-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-Astrophysical TeraHertz Large Area Survey (H-ATLAS), selected to have a similar stellar mass to the SMGs. The z > 1 SMGs have an average star formation rate (SFR) of 390^{+80}_{-70} M⊙ yr-1, which is 120 times that of the low-redshift sample matched in stellar mass to the SMGs (SFR = 3.3 ± 0.2 M⊙ yr-1). The SMGs harbour a substantial mass of dust (1.2^{+0.3}_{-0.2}× {10}^9 M⊙), compared to (1.6 ± 0.1) × 108 M⊙ for low-redshift dusty galaxies. At low redshifts, the dust luminosity is dominated by the diffuse interstellar medium, 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.