4) Debris at the low-mass end: predictions of stellar streams around the LMC and its siblings

Abstract: The number of Milky Way satellites and stellar streams originating from dwarf galaxies have tremendously increased over the past years, and some extragalactic streams have been observed as well. Interestingly a number of Milky Way satellites are found likely to have entered the Milky Way as satellites of the LMC, and there are even suggestions of stellar streams around the LMC itself. While LCDM predicts that the dark matter subhalo mass function is nearly self-similar, this is not true for subhalo baryon fractions, and accretion rates. We therefore expect massive galaxies and dwarf galaxies to have similar amounts of dark matter subhalos surrounding them but widely different stellar halo and debris structures. Observed differences in debris structures will therefore offer new insights into hierarchical structure formation on small scales as well as how the baryons occupy dark matter structures at the low-mass end. Future surveys such as the Nancy Roman Space Telescope (WFIRST) and the Vera Rubin Observatory’s LSST will enable us to probe the stellar halos of dwarf galaxies and potentially detect substructure surrounding dwarfs. In this talk, I will discuss our predictions for the existence of stellar halos and the probabilities of observing stellar streams 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. We predict whether formed substructure will be bright and long-lived enough to be observed by the current and next generation of telescopes, and what we can learn from these observations. Moreover, we connect our predictions for external LMC-sized dwarf galaxies to the LMC itself and to the Milky Way satellites and other debris that may have originated from the LMC.

Bio: Tjitske Starkenburg is a Postdoctoral Fellow at the Center for Interdisciplinary Exploration and Research in Astrophysics of Northwestern University. She studies galaxy formation and evolution and aims to link key episodes in (dwarf) galaxy evolution to observational evidence through analyzing galaxy simulations, building mock observational surveys, and performing detailed comparisons to observed data. She is particularly enthusiastic about improving comparisons between theory and observations, for example through applying data-driven methods.Tjitske is interested in combining information from dynamics, kinematics, morphology, and stellar populations to understand how galaxies evolve under influence of internal and external physical processes, and she believes that uncommon, or outlier galaxies may provide key insights into galaxy evolution physics.