The Drivers of Cosmic Dust Temperature Evolution

TL;DR

This study uses cosmological simulations with dust physics to explore how galaxy dust temperatures evolve with redshift, identifying key physical drivers and providing a practical relation for estimating dust-to-gas ratios in high-redshift galaxies.

Contribution

It introduces a semi-analytic galaxy formation model with explicit dust treatment, linking dust temperature evolution to galaxy properties and offering a new relation to estimate dust-to-gas ratios.

Findings

Dust temperature increases with redshift, aligning with observations.

Star formation rate surface density and dust-to-gas ratio are primary drivers of dust temperature.

Variations in dust grain size and composition have minimal impact on dust temperature.

Abstract

Observations of the rest-frame far-infrared (far-IR) emission of galaxies suggest a mild increase of dust temperature $T_{\rm dust}$ with redshift, although constraining $T_{\rm dust}$ in high-redshift systems remains challenging due to limited sampling of the far-IR spectral energy distribution (SED). We present and discuss the redshift evolution of $T_{\rm dust}$ predicted by a cosmological galaxy evolution simulation with dust treatment, and interpret its dependence on other galaxy physical properties. We use a semi-analytic model of galaxy formation that includes an explicit treatment of dust, post-processed with radiative transfer. Dust temperatures are derived by applying modified blackbody SED fitting to the simulated galaxies, mirroring the methodology adopted in most observational studies. The dust temperature of simulated galaxies increases with redshift, in broad agreement with observational results. A feature-importance analysis reveals that the star formation rate surface density $\Sigma_{\rm SFR}$ and the dust-to-gas ratio (DTG) are the main drivers of dust temperature, tracing the intensity of the interstellar radiation field and the optical depth of warm molecular clouds, respectively. Galaxies with higher star formation rate surface density and lower DTGs $-$ common conditions at high$-z$ $-$ are associated with warmer dust. We provide a simple relation to estimate DTG from $\Sigma_{\rm SFR}$, $T_{\rm dust}$, and redshift. Variations in dust grain size and chemical composition have a negligible impact on $T_{\rm dust}$. Our results are particularly relevant to the study of dust properties with observations of high-z galaxies, where far-IR dust emission is not fully sampled.