Axion Relic Pockets -- a theory of dark matter

TL;DR

This paper introduces axion relic pockets, a novel dark matter model where regions of false vacuum stabilized by trapped axion gas form during a first-order phase transition, offering a simple and testable alternative to existing theories.

Contribution

It presents a new dark matter framework based on axion physics and phase transitions, with unique macroscopic properties depending only on the transition temperature.

Findings

Formation of axion relic pockets during phase transitions

Distinct phenomenology from other dark matter models

Potential observational signatures in gamma-ray and astrophysical data

Abstract

We propose a new theory of dark matter based on axion physics and cosmological phase transitions. We show that theories in which a gauge coupling increases through a first-order phase transition naturally result in `axion relic pockets': regions of relic false vacua stabilised by the pressure from a kinematically trapped, hot axion gas. Axion relic pockets provide a viable and highly economical theory of dark matter: the macroscopic properties of the pockets depend only on a single parameter (the phase transition temperature). We describe the formation, evolution and present-day properties of axion relic pockets, and outline how their phenomenology is distinct from existing dark matter paradigms. We briefly discuss how laboratory experiments and astronomical observations can be used to test the theory, and identify gamma-ray observations of magnetised, dark-matter-dense environments as particularly promising.