Speaker
Description
Self-interacting dark matter (SIDM) provides a promising solution to small-scale structure anomalies, yet a unified explanation across mass scales remains challenging. Recent dwarf galaxy surveys favor a relatively small cross section of $\sim 0.3 \rm cm^2/g$---insufficient to induce core collapse---while strong lensing signals in galaxy clusters require dense inner subhalos typically associated with much larger cross sections. We demonstrate that this tension can be resolved in two-component SIDM models, where even modest inter-component interactions lead to efficient mass segregation in massive halos. This enhancement occurs without requiring large self-interaction rates, as the strength of SIDM effects scales with the scale density $\rho_s$ and radius $r_s$ as $\sigma_{\rm eff}/m r_s \rho_s^{3/2}$. Consequently, the impact is amplified in cluster subhalos, where both $\rho_s$ and $r_s$ are large, while remaining insignificant in dwarf galaxies. Using a set of cosmological zoom-in simulations of clusters and high-resolution controlled simulations of dwarf halos, we show that this framework can simultaneously reproduce cored dwarfs and cuspy cluster substructures. Our results highlight two-component SIDM with mass segregation as a unified and testable framework for explaining structural features of dark matter halos that are otherwise puzzling.
