The Universal Evolution of SIDM Halos

A self-interacting dark matter (SIDM) halo begins to thermalize once its age is comparable to the (inverse of the) self-interaction rate. Such thermalized self-gravitating systems are know to be unstable due to the so-called "Gravo-Thermal Catastrophe”. With the aim of better understanding the cosmological evolution and fate of SIDM halos, we study the gravothermal evolution of halos in the presence of generic (non-relativistic) interactions. Surprisingly, we find that the role of particle physics is largely reduced to setting the timescale of an otherwise universal halo evolution. As a consequence, an initial NFW can be simply matched to a corresponding late time SIDM halo.