Dark Matter Ultraviolet Freeze-in in General Reheating Scenarios

TL;DR

This paper investigates how the process of cosmic reheating influences the ultraviolet freeze-in production of dark matter, providing a generalized framework and exploring various scenarios including gravitational production.

Contribution

It introduces a general parametrization of reheating dynamics affecting dark matter production and derives a comprehensive framework for inflaton decay scenarios.

Findings

Revealed the dependence of dark matter production on reheating dynamics.

Identified viable parameter spaces for gravitational dark matter production.

Addressed constraints from CMB observations on reheating scenarios.

Abstract

The dynamics of cosmic reheating, that is, on how the energy stored in the inflaton is transferred to the standard model (SM) thermal bath, is largely unknown. In this work, we show that the phenomenology of the nonbaryonic dark matter (DM) ultraviolet freeze-in production strongly depends on the dynamics of the cosmic-reheating era. Using a general parametrization for the Hubble expansion rate and SM temperature, we thoroughly investigate DM production during reheating, not only recovering earlier findings that focused on specific cases, but also exploring alternative scenarios. Additionally, we derive a generalized framework for DM production via inflaton decays and identify the viable parameter space, while simultaneously addressing constraints from CMB observations. As illustrative examples, we explore gravitational DM production through scatterings of SM particles or inflatons, deriving well-defined parameter regions for these scenarios.