Neutralino Relic Density Enhancement in Non-Standard Cosmologies

TL;DR

This paper explores how non-standard early universe models can significantly increase neutralino relic abundance, impacting dark matter predictions and detection prospects.

Contribution

It demonstrates that non-standard cosmologies can enhance neutralino relic density by up to six orders of magnitude, broadening viable dark matter models.

Findings

Neutralino relic density can be increased by up to six orders of magnitude in non-standard cosmologies.

Supersymmetric models with large annihilation cross sections can explain all dark matter.

Enhanced relic abundance leads to higher indirect detection rates.

Abstract

The thermal relic abundance of species critically depends on the assumed underlying cosmological model. In the case of neutralinos, freeze-out takes place long before Big Bang Nucleosynthesis, which provides the strongest constraint on the evolution of the Hubble parameter in the Early Universe. We show that non-standard cosmologies, such as models featuring a quintessential scalar field or primordial anisotropies, can lead to large enhancements in the neutralino relic abundance, up to six orders of magnitudes. Within these scenarios, supersymmetric models with large neutralino annihilation cross sections may account for the whole inferred amount of cold dark matter, yielding on the other hand large indirect detection rates.