Cyclotron damping and Faraday rotation of gravitational waves

TL;DR

This paper investigates how gravitational waves interact with a magnetized plasma, revealing cyclotron damping or growth, polarization-dependent dispersion, and Faraday rotation effects, depending on plasma conditions and particle distributions.

Contribution

It introduces a detailed analysis of gravitational wave propagation in a plasma with magnetic fields, highlighting effects like cyclotron damping, polarization-dependent dispersion, and Faraday rotation.

Findings

Gravitational waves can be damped or amplified via cyclotron resonance.

Magnetic fields cause polarization-dependent dispersion of gravitational waves.

Faraday rotation of gravitational waves occurs due to magnetic field-induced birefringence.

Abstract

We study the propagation of gravitational waves in a collisionless plasma with an external magnetic field parallel to the direction of propagation. Due to resonant interaction with the plasma particles the gravitational wave experiences cyclotron damping or growth, the latter case being possible if the distribution function for any of the particle species deviates from thermodynamical equilibrium. Furthermore, we examine how the damping and dispersion depends on temperature and on the ratio between the cyclotron- and gravitational wave frequency. The presence of the magnetic field leads to different dispersion relations for different polarizations, which in turn imply Faraday rotation of gravitational waves.