UC Irvine

In self-interacting dark matter (SIDM) halos undergoing gravothermal evolution, the cores of halos are driven into the short-mean-free-path (SMFP) regime and undergo core collapse. In this dissertation, I study generic SIDM models with velocity-dependent cross-sections and elastic scattering, in SIDM halos experiencing gravothermal collapse. We study the structure and dynamics of halo cores in the SMFP and discover a new approximate universality deep in the SMFP regime. This new SMFP universality allows for the mapping of velocity- dependent cross sections to constant ones in this regime, offering improved predictions for physics occurring in the SMFP evolution of SIDM halos. We devise a semi-analytic recipe to predict the entire SMFP evolution of halos with our newfound SMFP universality by relating this new phase to the long-mean-free-path (LMFP) regime. This methodology streamlines the procedure of acquiring core properties within the SMFP regime and allows for estimates of the minimum mass of the black hole left behind, using simply the initial halo characteristics and particle physics parameters.