Dark Matter Halos as Particle Colliders: A Unified Solution to Small-Scale Structure Puzzles from Dwarfs to Clusters

摘要

Astrophysical observations spanning dwarf galaxies to galaxy clustersindicate that dark matter (DM) halos are less dense in their central regionscompared to expectations from collisionless DM N-body simulations. Usingdetailed fits to DM halos of galaxies and clusters, we show thatself-interacting DM (SIDM) may provide a consistent solution to the DM deficitproblem across all scales, even though individual systems exhibit a widediversity in halo properties. Since the characteristic velocity of DM particlesvaries across these systems, we are able to measure the self-interaction crosssection as a function of kinetic energy and thereby deduce the SIDM particlephysics model parameters. Our results prefer a mildly velocity-dependent crosssection, from $\sigma/m \simeq 2\; {\rm cm^2/g}$ on galaxy scales to $\sigma/m\simeq 0.1\; {\rm cm^2/g}$ on cluster scales, consistent with the upper limitsfrom merging clusters. Our results dramatically improve the constraints on SIDMmodels and may allow the masses of both DM and dark mediator particles to bemeasured even if the dark sector is completely hidden from the Standard Model,which we illustrate for the dark photon model.