Constraining self-interacting dark matter with dwarf spheroidal galaxies and high-resolution cosmological N -body simulations

We study the density structures of dark matter subhalos for both cold dark matter and self-interacting dark matter models using high-resolution cosmological N -body simulations. We quantify subhalo's central density at 150 pc from the center of each subhalo at the classical dwarf spheroidal and ultrafaint dwarf scales found in Milky-Way sized halos. By comparing them with observations, we find that the self-interacting scattering cross section of σ /m <3 cm² g^-1 is favored. Due to the combination of hosts' tide and self-interactions, the central density of subhalos with small pericenter shows a noticeable difference between the cold and the self-interacting models, indicating that Milky-Way satellites with small pericenter are ideal sites to further constrain the nature of dark matter by future large spectroscopic surveys.