Small Scale Structure: A Local and Cosmological View of Dwarf Galaxies and Their Satellites
Dwarf galaxies are sensitive tests of the LCDM cosmological model and the physics of galaxy formation. We use numerical simulations to investigate the interaction between galaxies, their DM halos, and their satellites. We study zoom-in simulations from the Feedback In Realistic Environments (FIRE) project to show that Large Magellanic Cloud (LMC)-mass centrals destroy fewer of their dark subhalos compared to Milky Way (MW)-mass centrals. Gaia proper motions provide new insight into the satellite population of the LMC, bringing it to 5 with M_star > 10^4 M_sun, consistent with our simulated satellite populations. The star formation histories of FIRE LMC-satellites have greater diversity than those of similar mass centrals and that the overall stellar mass dependence of the quenched fraction is consistent with previous results for MW satellites. LMC-mass halos can quench their satellites via ram-pressure stripping, sometimes aided by internal feedback processes. Gravitational interactions between the host and satellites can form stellar tidal streams around the host, which should be detectable in observations. We then use idealized simulations of a dwarf galaxy with both the Springel & Hernquist 2003 (SH03) model and the SMUGGLE model to investigate feedback-driven core formation. SMUGGLE produces bursty star formation, high gas densities, and large fluctuations of gas content within the inner regions leading to the growth of a core, while the SH03 does not produce a feedback-driven core formation. We implement variations on the SMUGGLE model which all form cores, suggesting that detailed modeling is more important than parameter tuning. None of the SMUGGLE models produce gas components with rotational velocity profiles that trace the DM potential, systematically rising slower than the circular velocity profile. The rotational velocity profiles exhibit significant variation across time, suggesting that a diversity of rotation curves could be produced by feedback-driven gas kinematics alone.