The Pressure of Misalignment Axions: a Difference from WIMPs in Galaxy Formation?

TL;DR

This paper explores how axions, produced via different mechanisms, influence galaxy formation differently from WIMPs due to their unique pressure properties, potentially leading to observable effects.

Contribution

It highlights the distinct pressure effects of misalignment-produced axions compared to WIMPs and discusses their implications for galaxy formation.

Findings

Axions from the misalignment mechanism exert extra pressure.

Differences in pressure may lead to observable galaxy formation signatures.

Potential for new observational tests distinguishing axions from WIMPs.

Abstract

Two populations of axions can contribute to cold dark matter: the classical field produced via the misalignment mechanism, and the modes produced in the decay of strings. The classical field has extra pressure, as compared to WIMPs, which could have observable consequences in non-linear galaxy formation.