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Debris at the low-mass end: predictions for stellar halos, streams and shells around the LMC and its siblings

Presentation #403.02 in the session “Galactic Streams and Structures”.

Published onJun 01, 2021
Debris at the low-mass end: predictions for stellar halos, streams and shells around the LMC and its siblings

I will present predictions for the stellar halos and tidal debris like stellar streams and shells for LMC-sized galaxies in the field, based on semi-analytic and dynamical modeling. I will also discuss what we can learn from future observations in this regime to constrain hierarchical galaxy formation at the low-mass end.

The number of Milky Way satellites and substructures in the stellar halo have tremendously increased over the past years, providing constraints on the accretion history of our galaxy. Additionally, while ongoing observational efforts have highlighted the diversity in stellar halos, simulations are illustrating how this diversity may connect to the merger histories of the individual galaxies. However, most of this work has focused on Milky Way-mass systems or larger. In contrast, I will highlight what we can learn from the stellar halos of lower-mass systems utilizing the current and upcoming low-surface brightness discovery space.

Based on the stellar mass-halo mass relation, massive galaxies and dwarf galaxies are expected to have widely different stellar accretion fractions and different stellar halos. Observed differences in debris structures will therefore offer new insights into hierarchical structure formation on small scales, and may provide constraints on the stellar mass-halo mass relation at the low-mass end. Future surveys such as EUCLID, the Nancy Grace Roman Space Telescope, and the Vera Rubin Observatory will enable us to probe the stellar halos of dwarf galaxies and potentially detect substructure surrounding dwarfs.

We make predictions for the stellar halos and the morphology and observability of stellar tidal debris structures around LMC-type dwarf galaxies. We study the accretion and evolution of substructure onto LMC-sized dwarf galaxies in a cosmological context and for a statistically large sample of dwarf galaxies based on a semi-analytic approach. Our approach allows us to marginalize over modeling parameters, and we provide estimates of how strongly observable debris structure properties depend on galaxy formation and dynamical assumptions, building toward a framework to facilitate the interpretation of observations by the current and next generation of telescopes.

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