Dust in the Average Galaxy: Attenuation, Emission, and Opacity from 0<z<7

Résumé fourni par la source

We present constraints on the dust emission and attenuation properties of galaxies across 0 M ⋆ > 10 10.5 M ⊙ . We derive empirical relationships for the effective attenuation, dust temperature, fraction of star formation that is unobscured, and dust-to-stellar mass ratio as functions of redshift and stellar mass. We separate the first order effect of star/dust geometry from dust grain properties by combining constraints on the IR SED, UV SED, and dust mass surface density. Importantly, we measure over an order of magnitude decrease in κ U V / κ F I R –the ratio of dust mass absorption coefficients in the UV at 1600Å and FIR at 500 μ m–from z~0 to z~7. A depressed κ U V / κ F I R is consistent with a deficit of small dust grains, possibly attributable to the intense radiation fields of high- z star formation; indeed, we find a redshift-invariant inverse relationship between κ U V / κ F I R and Σ S F R . Most evolution in the dust-to-stellar ratio is at z < 1 , the product of mild downward evolution in the dust-to-gas ratio combined with steep evolution in the gas-to-stellar ratio. The significant evolution and dynamic range of κ U V / κ F I R and prevailing disconnect between the UV/optical and FIR regimes emphasize that direct dust constraints are irreplaceable for the majority of star-forming galaxies at z < 7 , not just the most extreme star-formers.

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