A Dusty Locale: Evolution of Galactic Dust Populations from Milky Way to Dwarf-Mass Galaxies

Observations indicate dust populations vary between galaxies and within them,suggesting a complex life cycle and evolutionary history. Here we investigatethe evolution of galactic dust populations across cosmic time using a suite ofcosmological zoom-in simulations from the Feedback in Realistic Environments(FIRE) project, spanning $M_{\rmvir}=10^{9-12}M_{\odot};\,M_{*}=10^{6-11}\,M_{\odot}$. Our simulationsincorporate a dust evolution model that accounts for the dominant sources ofdust production, growth, and destruction and follows the evolution of specificdust species with set chemical compositions. All galactic dust populations inour suite exhibit similar evolutionary histories, with gas-dust accretion beingthe dominant producer of dust mass for all but the most metal-poor galaxies.The onset of efficient gas-dust accretion occurs above a `critical' metallicitythreshold ($Z_{\rm crit}$). Due to this threshold, our simulations reproduceobserved trends between galactic D/Z and metallicity and element depletiontrends in the ISM. Furthermore, $Z_{\rm crit}$ varies between dust species dueto differences in key element abundances, dust physical properties, and lifecycle processes resulting in $Z_{\rm crit} \sim 0.05 Z_{\odot},\,0.2Z_{\odot},\,0.5 Z_{\odot}$ for metallic iron, silicates, and carbonaceous dust,respectively. These variations could explain the lack of small carbonaceousgrains observed in the Magellanic Clouds. We also find a delay between theonset of gas-dust accretion and when a dust population reaches equilibrium,which we call the equilibrium timescale ($\tau_{\rm eq}$). The relation between$\tau_{\rm eq}$ and the metal enrichment timescale of a galaxy, determined byits recent evolutionary history, can contribute to the scatter in the observedrelation between galactic D/Z and metallicity.