Audible Axion Magnetogenesis: Linking Intergalactic Magnetic Fields and Gravitational Waves

TL;DR

This paper proposes a mechanism where axion-like particles generate gravitational waves and intergalactic magnetic fields through a supercooling phase and tachyonic instability, linking dark matter physics with observable cosmological signals.

Contribution

It introduces a novel axion-based model that produces detectable gravitational waves and magnetic fields, connecting particle physics with cosmological observations.

Findings

Exponential photon production via tachyonic instability occurs during supercooling.

Generated magnetic fields exceed observational lower bounds from blazar data.

The model predicts gravitational wave signatures within detectable ranges.

Abstract

Identifying dark matter candidates that simultaneously generate multiple observable cosmological signatures is a key goal in connecting particle physics with upcoming observations. Axion-like particles coupled to the Standard Model photon offer a promising framework. In the trapped misalignment mechanism, the onset of axion oscillations is delayed, inducing a period of supercooling in the early Universe. This can lead to exponential production of photon quanta via a tachyonic instability, generating observable gravitational wave signatures. Simultaneously, reheating of the Standard Model plasma produces strong, helical magnetic fields on intergalactic scales. The parameter space most promising for gravitational wave detection yields magnetic field strengths that exceed lower bounds from blazar observations.