Self-Interacting Dark Matter and the Origin of Ultra-Diffuse Galaxies
  NGC1052-DF2 and -DF4
  Observations of ultra-diffuse galaxies NGC 1052-DF2 and -DF4 show they may
contain little dark matter, challenging our understanding of galaxy formation.
Using controlled N-body simulations, we explore the possibility that their
properties can be reproduced through tidal stripping from the elliptical galaxy
NGC 1052, in both cold dark matter (CDM) and self-interacting dark matter
(SIDM) scenarios. To explain the dark matter deficiency, we find that a CDM
halo must have a very low concentration so that it can lose sufficient inner
mass in the tidal field. In contrast, SIDM favors a higher and more reasonable
concentration as core formation enhances tidal mass loss. Final stellar
distributions in our SIDM benchmarks are more diffuse than the CDM one, and
hence the former are in better agreement with the data. We further show that a
cored CDM halo model modified by strong baryonic feedback is unlikely to
reproduce the observations. Our results indicate that SIDM is more favorable
for the formation of dark-matter-deficient galaxies.
