# Reconstructing Non-standard Cosmologies with Dark Matter

## TL;DR

This paper explores how non-standard cosmological models can explain dark matter production, especially when the WIMP mechanism does not align with standard radiation-dominated universe assumptions.

## Contribution

It reconstructs possible non-standard cosmologies that enable the WIMP dark matter production mechanism to be viable beyond the standard model.

## Key findings

- Identifies conditions under which non-standard cosmologies can produce the correct dark matter abundance.
- Provides a framework to reconstruct cosmological histories compatible with dark matter observations.
- Highlights the importance of early Universe expansion history in dark matter genesis.

## Abstract

Once dark matter has been discovered and its particle physics properties have been determined, a crucial question rises concerning how it was produced in the early Universe. If its thermally averaged annihilation cross section is in the ballpark of few$\times 10^{-26}$ cm$^3$/s, the WIMP mechanism in the standard cosmological scenario (i.e. radiation dominated Universe) will be highly favored. If this is not the case one can either consider an alternative production mechanism, or a non-standard cosmology. Here we study the dark matter production in scenarios with a non-standard expansion history. Additionally, we reconstruct the possible non-standard cosmologies that could make the WIMP mechanism viable.