# Axion production from primordial magnetic fields

## TL;DR

This paper explores how primordial magnetic fields can produce axionlike particles (ALPs), potentially explaining dark matter and relating to recent astrophysical signals, with implications for early universe magnetogenesis.

## Contribution

It identifies specific ALP mass and coupling regions compatible with dark matter observations influenced by primordial magnetic fields.

## Key findings

- A parameter space where ALPs account for dark matter.
- Exclusion of some ALP parameters due to overproduction.
- Implications for primordial magnetogenesis scenarios.

## Abstract

Production of axionlike particles (ALPs) by primordial magnetic fields may have significant impacts on cosmology. We discuss the production of ALPs in the presence of the primordial magnetic fields. We find a region of the ALP mass and photon coupling which realizes the observed properties of the dark matter with appropriate initial conditions for the magnetic fields. This region may be interesting in light of recent indications for the 3.5 keV lines from galaxy clusters. For a small axion mass, a region of previously allowed parameter spaces is excluded by overproduction of ALPs as a hot/warm dark matter component. Since the abundance of ALPs strongly depends on the initial conditions of primordial magnetic fields, our results provide implications for scenarios of magnetogenesis.