Simulating the "hidden giant" in cold and self-interacting dark matter
  models
  We perform a series of controlled N-body simulations to study realizations of
the recently discovered Antlia 2 galaxy in cold dark matter (CDM) and
self-interacting dark matter (SIDM) scenarios. Our simulations contain six
benchmark models, where we vary the initial halo concentration and the
self-scattering cross section. We adopt well-motivated initial stellar and halo
masses, and our fiducial orbit has a small pericenter. After evolving in the
Milky Way's tidal field, the simulated galaxies experience significant mass
loss and their stellar distributions expand accordingly. These tidal effects
are more prominent if the initial halo concentration is lower and if the
self-scattering cross section is larger. Our results show that Antlia 2-like
galaxies could be realized in CDM if the halo concentration is low and the
stellar distribution is diffuse at the infall time, while these conditions
could be relaxed in SIDM. We also find all the simulated galaxies predict
approximately the same stellar velocity dispersion after imposing selection
criteria for stellar particles. This has important implications for testing
dark matter models using tidally disturbed systems.
