Gravothermal evolution of dark matter halos with differential elastic scattering

We study gravothermal evolution of dark matter halos in the presence differential self-scattering that has strong velocity and angular dependencies. design controlled N-body simulations to model Rutherford Moller scatterings halo, follow its both core-expansion -collapse phases. The show commonly-used transfer cross section underestimates effects self-interactions, but viscosity provides an accurate approximation for modeling angular-dependent scattering. investigate thermodynamic properties find three moments Boltzmann equation under fluid are satisfied. further propose a constant effective section, which integrates over halo's characteristic dispersion with weighting kernels motivated by kinetic theory heat conduction. good most halo evolution. It indicates we can map astrophysical constraints on self-interacting SIDM velocity- scatterings.