Astrophysics Seminar: Dr. Caleb Choban, Indiana University

Dr. Caleb Choban
Postdoctoral Fellow
Department of Astonomy

Indiana University

 

Observations of the Milky Way (MW) and the Large and Small Magellanic Clouds (LMC & SMC) reveal significant variations in their respective dust populations. Dust extinction curves and infrared emissions exhibit a dramatic difference in the abundance of small carbonaceous grains. Gas-phase element depletions indicate a decreasing fraction of metals locked in dust (dust-to-metals ratio; D/Z) and considerable variation in dust chemical composition. The exact causes of these variations are unknown, but dust evolution models coupled with galaxy evolution simulations can help elucidate this issue.

 

Here, I present a suite of cosmological zoom-in simulations of MW to dwarf halo-mass galaxies utilizing a dust evolution model I developed and incorporated into the GIZMO code and coupled with FIRE-2 stellar feedback and ISM physics. I 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 MW, dominates for the majority of the galaxy's life. I also discover that the onset of rapid dust growth via accretion differs between dust species, arising from differences in their 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 modeling of individual dust species evolution.