Self-Interacting Dark Matter in the Most Massive Subhalos of the Milky Way

We present a suite of cosmological zoom-in simulations of cold dark matter (CDM) and self-interacting dark matter (SIDM) halos within the “Feedback in Realistic Environments” (FIRE) project. We simulate these halos with and without baryonic physics. At z = 0, our simulated halos have virial masses of 10¹² solar masses and we use self-interaction cross sections of 1 and 10 cm² g^-1. We study the most massive subhalos of these hosts, selected through their maximum circular velocities. We find that SIDM decreases radial subhalo abundance, lowers the magnitude of subhalos’ circular velocity profiles, and decreases the subhalos’ central densities at inner regions. We find no evidence of gravothermal core-collapse in the most massive subhalos. “We acknowledge support from the NSF REU grant AST-1757983 (PI: Jogee).