Self-Interacting Dark Matter and the Origin of NGC1052-DF2 and -DF4

Observations of ultra-diffuse galaxies NGC1052-DF2 and -DF4 show they contain little dark matter, challenging our understanding of galaxy formation. Using controlled N-body simulations, we explore the possibility to reproduce their properties through tidal stripping from elliptical galaxy NGC1052, 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 mass in the tides. In contrast, SIDM favors a higher and more reasonable concentration as core formation enhances tidal mass loss. Stellar distributions in our SIDM benchmarks are more diffuse than CDM one, and hence the former provide a better match to the data. We further show that the presence of stellar particles is critical for preventing the halos from being totally disrupted and discuss its implications. Our results indicate that the dark matter-deficient galaxies may provide important tests for the nature of dark matter.