2017ApJ...843...71K

At z=1–3, the formation of new stars is dominated by dusty galaxies whose far-IR emission indicates they contain colder dust than local galaxies of a similar luminosity. We explore the reasons for the evolving IR emission of similar galaxies over cosmic time using (1) local galaxies from GOALS (L_IR=10¹¹–10¹² L_☉), (2) galaxies at z∼0.1–0.5 from 5MUSES (L_IR=10¹⁰–10¹² L_☉), and (3) IR luminous galaxies spanning z=0.5–3 from GOODS and Spitzer xFLS (L_IR 10¹¹ L_☉). All samples have Spitzer mid-IR spectra, and Herschel and ground-based submillimeter imaging covering the full IR spectral energy distribution, allowing us to robustly measure L_IR^SF, T_dust, and M_dust for every galaxy. Despite similar infrared luminosities, z 0.5 dusty star-forming galaxies (DSFG) have a factor of 5 higher dust masses and 5 K colder temperatures. The increase in dust mass is linked to an increase in the gas fractions with redshift, and we do not observe a similar increase in stellar mass or star formation efficiency. L₁₆₀^SF/L₇₀^SF, a proxy for T_dust, is strongly correlated with L_IR^SF/M_dust independently of redshift. We measure merger classification and galaxy size for a subsample, and there is no obvious correlation between these parameters and L_IR^SF/M_dust or L₁₆₀^SF/L₇₀^SF. In DSFG, the change in L_IR^SF/M_dust can fully account for the observed colder dust temperatures, suggesting that any change in the spatial extent of the interstellar medium is a second-order effect.