Self-heating dark matter via semi-annihilation

Understand

The freeze-out of dark matter (DM) depends on the evolution of the DM temperature.

• The DM temperature does not have to follow the standard model one, when the elastic scattering is not sufficient to maintain the kinetic equilibrium.
• We study the temperature evolution of the semi-annihilating DM, where a pair of the DM particles annihilate into one DM particle and another particle coupled to the standard model sector.
• We find that the kinetic equilibrium is maintained solely via semi-annihilation until the last stage of the freeze-out.