The Evolving Interstellar Medium of Star-forming Galaxies, as Traced by Stardust*

Abstract

We analyze the far-infrared (FIR) properties of ∼5000 star-forming galaxies at z < 4.5, drawn from the deepest, super-deblended catalogs in the GOODS-N and COSMOS fields. We develop a novel panchromatic spectral energy distribution fitting algorithm, Stardust , that models the emission from stars, active galactic nuclei (AGNs), and infrared dust emission, without relying on energy balance assumptions. Our code provides robust estimates of the UV−optical and FIR physical parameters, such as the stellar mass ( M * ), dust mass ( M dust ), infrared luminosities ( L IR ) arising from AGN and star formation activity, and the average intensity of the interstellar radiation field (〈 U 〉). Through a set of simulations we quantify the completeness of our data in terms of M dust , L IR , and 〈 U 〉 and subsequently characterize the distribution and evolution of these parameters with redshift. We focus on the dust-to-stellar mass ratio ( f dust ), which we parameterize as a function of cosmic age, stellar mass, and specific star formation rate. The f dust is found to increase by a factor of 10 from z = 0 to z = 2 and appears to remain flat at higher z , mirroring the evolution of the gas fraction. We also find a growing fraction of warm to cold dust with increasing distance from the main sequence, indicative of more intense interstellar radiation fields, higher star formation efficiencies, and more compact star-forming regions for starburst galaxies. Finally, we construct the dust mass functions (DMFs) of star-forming galaxies up to z = 1 by transforming the stellar mass function to DMF through the scaling relations derived here. The evolution of f dust and the recovered DMFs are in good agreement with the theoretical predictions of the Horizon-AGN and IllustrisTNG simulations.