The observability of stellar halos and stellar streams in external galaxies

I will present predictions for the observability of extragalactic stellar halos and their tidal debris, such as stellar streams originating from dwarf galaxies and globular clusters, with the Roman Space Telescope and the Rubin Observatory. I will highlight how this low-surface brightness discovery space provides unique constraints on hierarchical galaxy formation at the low-mass end.

Stellar halos can be amazingly rich records of their host galaxy’s history, and because the presence of (disrupted) lower-mass satellites and globular clusters also fundamentally of galaxy formation at lower masses. However, most of the past work has focused on Milky Way-mass systems or larger while the galaxies in our nearby universe are predominantly dwarfs. In particular the stellar halos and accretion histories of these dwarf galaxies have the potential to offer novel insights into galaxy formation at the low-mass end and in the early universe.

I will describe work on the observability of stellar halos and tidal debris of LMC-sized galaxies, constraints on resolved observations of globular cluster stellar streams in M31 and other nearby galaxies, and the evolution of globular cluster streams during hierarchical galaxy evolution, facilitating the interpretation of observations by the next generation of telescopes.