Astrophysics Seminar: Dr. Anna Wright, Flatiron Institute

Observations have shown that faint extended stellar halos primarily composed of tidal debris from infalling dwarf satellites are ubiquitous around massive galaxies. Recent surveys probing the outskirts of low mass — or "dwarf" — galaxies have revealed similar structures around many dwarfs in the local universe. However, the origins of the stars that populate the stellar halos of dwarf galaxies is unknown. The contribution from ex situ stars (i.e., those accreted from other galaxies) can teach us about the merger histories of dwarfs and the steepness of the stellar mass—halo mass relation in the ultra-faint regime, while the contribution from in situ stars (i.e., those formed in the dwarf and perturbed into halo orbits) can teach us about feedback processes and the gravitational potential of the dwarf itself. In this presentation, I will show new results from the “Marvelous Massive Dwarfs”, a suite of high resolution cosmological zoom-in simulations of dwarf galaxies run with ChaNGa. I will discuss the assembly histories of these dwarfs, with a focus on where accreted stars from satellites end up and how this shapes the morphology of the central dwarf and its stellar halo. I will also explore how my findings compare to recent results from the TRiangulum EXtended (TREX) and DELVE-DEEP/MADCASH surveys, which have discovered stellar halo-like structures around several local dwarf galaxies.