Electromagnetic radiation from axion condensates in a time dependent magnetic field

TL;DR

This paper investigates how time-dependent magnetic fields, such as those near neutron stars, can induce electromagnetic radiation from axion condensates, especially under resonance conditions with varying magnetic field frequencies.

Contribution

It introduces a model for axion-induced electromagnetic radiation in dynamic magnetic fields and explores resonance effects with time-varying magnetic field frequencies.

Findings

Resonant peaks in radiation occur when magnetic field frequency matches axion mass.

Time-varying magnetic fields can scan a range of axion masses for resonance.

Resonance can be enhanced in astrophysical scenarios like neutron star mergers.

Abstract

Time dependent magnetic fields can be sourced by spinning neutron stars, orbiting binaries and merging neutron stars. We consider electromagnetic radiation from axion condensates in the background of an alternating magnetic field. We find that a resonant peak in radiation can occur when the frequency of the alternating magnetic field is comparable with the axion mass scale. More interestingly, in situations where the frequency of the alternating magnetic field itself changes with time, as can be the case in binary mergers due to steady increase in orbital frequency, the resonant peak in radiation may occur for a range of axion mass scales scanned by the time-varying magnetic field frequency.