Hidden Sector Monopole Dark Matter with Matter Domination

TL;DR

This paper explores hidden-sector magnetic monopoles as dark matter candidates, analyzing their production via the Kibble-Zurek mechanism across various cosmological histories, including matter domination, and finds monopoles with masses up to 10^5 PeV could account for dark matter.

Contribution

It revisits topological dark matter with a focus on monopoles, considering diverse cosmological histories and deriving conditions for their relic abundance and mass.

Findings

Monopole masses of 1-10^5 PeV can explain dark matter abundance.

Early matter domination affects monopole relic density and required mass.

Monopole production is consistent with non-thermal cosmological scenarios.

Abstract

The thermal freeze-out mechanism for relic dark matter heavier than $O(10-100 $ TeV$)$ requires cross-sections that violate perturbative unitarity. Yet the existence of dark matter heavier than these scales is certainly plausible from a particle physics perspective, pointing to the need for a non-thermal cosmological history for such theories. Topological dark matter is a well-motivated scenario of this kind. Here the hidden-sector dark matter can be produced in abundance through the Kibble-Zurek mechanism describing the non-equilibrium dynamics of defects produced in a second order phase transition. We revisit the original topological dark matter scenario, focusing on hidden-sector magnetic monopoles, and consider more general cosmological histories. We find that a monopole mass of order ($1-10^5$) PeV is generic for the thermal histories considered here, if monopoles are to entirely reproduce the current abundance of dark matter. In particular, in a scenario involving an early era of matter domination, the monopole number density is always less than or equal to that in a pure radiation dominated equivalent provided a certain condition on critical exponents is satisfied. This results in a larger monopole mass needed to account for a fixed relic abundance in such cosmologies.