Universal gravothermal evolution of isolated self-interacting dark matter halos for velocity-dependent cross sections

Understand

We study the evolution of isolated self-interacting dark matter (SIDM) halos using spherically-symmetric gravothermal equations allowing for the scattering cross section to be velocity dependent.

• We focus our attention on the large class of models where the core is in the long mean free path regime for a substantial time.
• We find that the temporal evolution exhibits an approximate universality that allows velocity-dependent models to be mapped onto velocity-independent models in a well-defined way using the scattering timescale computed when the halo achieves its minimum central density.
• We show how this timescale depends on the halo parameters and an average cross section computed at the central velocity dispersion when the central density is minimum.