UC San Diego

Interstellar dust grains play prominent roles in physical processes across astronomical scales and affect all astronomical observations to varying degrees. However, our understanding of how dust evolves within galaxies and across cosmic time is incomplete.We investigate the dust life cycle and make predictions for the evolution of galactic dust populations across cosmic time by developing dust evolution models and integrating them into cosmological galaxy simulations.

In Chapter 2, we present two separate dust evolution models coupled with the ``Feedback In Realistic Environment'' (FIRE) model for stellar feedback and ISM physics. These models incorporate the main mechanisms comprising the dust life cycle but differ in their treatment of dust chemical composition and gas-dust accretion based on recent, contrasting approaches in the galaxy formation community. We test and compare these models in an idealized Milky Way-mass galaxy and find that both produce reasonable galaxy-integrated dust populations and predict gas-dust accretion as the main dust growth mechanism. However, only a model that simultaneously incorporates a physically motivated gas-dust accretion routine and tracks the evolution of specific dust species can reproduce observed spatial dust variability within the Milky Way, in both amount and composition.

In Chapter 3, we present a suite of cosmological galaxy simulations of Milky Way to dwarf halo-mass galaxies. These simulations utilize the dust evolution model presented in Chapter 2, which tracks the evolution of specific dust species and incorporates a physically motivated dust growth routine. We find that gas-dust accretion is the dominant producer of dust mass for all but the most metal-poor galaxies and, in the case of the Milky Way, dominates for the majority of the galaxy's life.We also discover that the onset of rapid growth via gas-dust accretion differs between dust species, arising from differences in element abundances, dust physical properties, and life cycles. These differences can explain the variable dust population, in both amount and composition, in the MW, LMC, and SMC and highlight the importance of accurate gas-dust accretion modeling for individual dust species.