Speaker
Description
In this talk, we will discuss the cosmological evolution of freeze-in dark matter models in the presence of an additional scalar component. Such a component can significantly modify the standard freeze-in scenario by altering both the expansion history of the Universe and the entropy evolution, resulting in either a suppression or an enhancement of the final dark matter abundance. As a concrete example, we will present the case of thermally produced gravitino dark matter. For a matter-like equation of state, the additional scalar field can induce substantial entropy production, leading to a significant dilution of the gravitino abundance and consequently allowing considerably larger reheating temperatures than in the standard cosmological scenario. In contrast, for a kination-like equation of state, the gravitino abundance is enhanced, resulting in a lower maximum reheating temperature compatible with the observed dark matter relic density.