GAMA/H-ATLAS: The Dust Opacity - Stellar Mass Surface Density Relation for Spiral Galaxies
astro-ph.CO
/ Authors
M. W. Grootes, R. J. Tuffs, C. C. Popescu, B. Pastrav, E. Andrae, M. Gunawardhana, L. S. Kelvin, J. Liske, M. Seibert, E. N. Taylor
and 25 more authors
A. W. Graham, M. Baes, I. K. Baldry, N. Bourne, S. Brough, A. Cooray, A. Dariush, G. De Zotti, S. P. Driver, L. Dunne, H. Gomez, A. M. Hopkins, R. Hopwood, M. Jarvis, J. Loveday, S. Maddox, B. F. Madore, M. J. Michałowski, P. Norberg, H. R. Parkinson, M. Prescott, A. S. G. Robotham, D. J. B. Smith, D. Thomas
/ Abstract
We report the discovery of a well-defined correlation between B-band face-on central optical depth due to dust, τ^f_B, and the stellar mass surface density, μ_{*}, of nearby (z < 0.13) spiral galaxies: log(τ^f_B) = 1.12(+-0.11)log(μ_{*}/M_sol kpc^2)-8.6(+-0.8). This relation was derived from a sample of spiral galaxies taken from the Galaxy and Mass Assembly (GAMA) survey and detected in the FIR/submm in the Herschel-ATLAS survey. Using a quantitative analysis of the NUV attenuation-inclination relation for complete samples of GAMA spirals categorized according to μ_{*} we demonstrate that this correlation can be used to statistically correct for dust attenuation purely on the basis of optical photometry and S'ersic-profile morphological fits. Considered together with previously established empirical relationships between stellar mass, metallicity and gas mass, the near linearity and high constant of proportionality of the τ^f_B-μ_{*} relation disfavors a stellar origin for the bulk of refractory grains in spiral galaxies, instead being consistent with the existence of a ubiquitous and very rapid mechanism for the growth of dust in the ISM. We use the τ^f_B-μ_{*} relation in conjunction with the radiation transfer model for spiral galaxies of Popescu & Tuffs (2011) to derive intrinsic scaling relations between specific star formation rate (sSFR), stellar mass, and μ_{*}, in which the attenuation of the UV light used to measure the SFR is corrected on an object-to-object basis. A marked reduction in scatter in these relations is achieved which is demonstrably due to correction of both the inclination-dependent and face-on components of attenuation. Our results are consistent with a picture of spiral galaxies in which most of the submm emission originates from grains residing in translucent structures, exposed to UV in the diffuse interstellar radiation field.