Probing star formation and ISM properties using galaxy disk inclination III: Evolution in dust opacity and clumpiness between redshift 0.0 < z < 0.7 constrained from UV to NIR
Abstract
(Abridged) In this paper, we use the Tuffs et al. attenuation - inclination models in ultraviolet (UV), optical, and near-infrared (NIR) bands to investigate the average global dust properties in galaxies as a function of stellar mass M*, stellar mass surface density μ*, star-formation rate SFR, specific star-formation rate sSFR, star-formation main-sequence offset dMS, and star-formation rate surface density SFR at redshifts z 0 and z 0.7. We use star-forming galaxies from SDSS ( 20000) and GAMA ( 2000) to form our low-z sample at 0.04 < z < 0.1 and star-forming galaxies from COSMOS ( 2000) for the sample at 0.6 <z < 0.8. We find that galaxies at z 0.7 have higher optical depth τBf and clumpiness F than galaxies at z 0. The increase in F hints that the stars of z 0.7 galaxies are less likely to escape their birth cloud, which might indicate that the birth clouds are larger. We also found that τBf increases with M* and μ*independent of sample and therefore redshift. We found no clear trends in τBf or F with SFR, which could imply that the dust mass distribution is independent of SFR. In turn, this would imply that the balance of dust formation and destruction is independent of the SFR. Based on an analysis of the inclination-dependence of the Balmer decrement, we find that reproducing the Balmer line emission requires not only a completely optically thick dust component associated with star forming regions, as in the standard Tuffs et al. model, but an extra component of optically thin dust within the birth clouds. This new component implies the existence of dust inside HII regions that attenuates the Balmer emission before it escapes through gaps in the birth cloud and we find it is more important in high-mass galaxies.