Self-interacting hidden sector dark matter, small scale galaxy structure anomalies, and a dark force

Understand

The short distance behavior of dark matter (DM) at galaxy scales exhibits several features not explained by the typical cold dark matter (CDM) with velocity-independent cross-section.

• We discuss a particle physics model with a hidden sector interacting feebly with the visible sector where a dark fermion self-interacts via a dark force with a light dark photon as the mediator.
• We study coupled Boltzmann equations involving two temperatures, one for each sector.
• We fit the velocity-dependent DM cross-section to the data from scales of dwarf galaxies to clusters consistent with relic density constraint.