Dark Matter freezeout in modified cosmological scenarios

Understand

We study the effects of modifying the expansions history of the Universe on Dark Matter freezeout.

• We derived a modified Boltzmann equation for freeze-out for an arbitrary energy density in the early Universe and provide an analytic approach using some approximations.
• We then look at the required thermally averaged cross sections needed to obtain the correct relic density for the specific case where the energy density consists of radiation plus one extra component which cools faster.
• We compare our analytic approximation to a numerical solutions.