Production of axions during scattering of Alfven waves by fast-moving Schwarzschild black holes

TL;DR

This paper proposes a new mechanism where fast-moving Schwarzschild black holes interacting with Alfven waves in magnetized plasma generate axions through electromagnetic anomalies caused by the black hole's motion.

Contribution

It introduces a novel process linking black hole motion and electromagnetic anomalies to axion production, expanding understanding of axion generation in astrophysical environments.

Findings

Black hole motion creates electromagnetic anomalies enabling axion production.

Super-Alfvenic black hole velocities prevent plasma screening of electric fields.

The mechanism links macroscopic black hole dynamics to microscopic axion generation.

Abstract

We discuss a novel mechanism of axion production during scattering of Alfven waves by a fast moving Schwarzschild black holes. The process couples classical macroscopic objects, and effectively large amplitude electromagnetic (EM) waves, to microscopic axions. The key ingredient is that the motion of a black hole (BH) across magnetic field creates classical non-zero second Poincare invariant, the electromagnetic anomaly (Lyutikov 2011). In the case of magnetized plasma supporting Alfven wave, it is the fluctuating component of the magnetic field that contributes to the anomaly: for sufficiency small BH moving with the super-Alfvenic velocity the plasma does not have enough time to screen the parallel electric field. This creates time-dependent $ {\bf E} \cdot {\bf B} \neq 0$, and production of axions via the axion-EM coupling.