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

We present constraints on the dust emission and attenuation properties of galaxies across 0<z<7 using JWST imaging from the COSMOS-Web Survey combined with deep FIR/(sub)millimeter data from Spitzer, Herschel, SCUBA-2, NIKA-2 and ALMA. We analyze over 500,000 galaxies to independently constrain attenuation in the rest-frame ultraviolet (UV) and optical as well as dust emission from stacked FIR spectral energy distributions (SEDs), enabling a direct comparison between the two. We find UV/optical attenuation systematically underpredicts IR luminosity by a factor of ~3x at 0.5<z<7 and up to an order of magnitude for 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.