Propagation Effects in Magnetized Transrelativistic Plasmas

TL;DR

This paper derives analytic expressions for polarization propagation effects in magnetized relativistic plasmas, bridging non-relativistic and ultra-relativistic regimes, with applications to astrophysical environments.

Contribution

It provides new analytic formulas for Faraday effects in high-temperature relativistic plasmas, filling gaps in existing models and improving plasma diagnostics.

Findings

Temperature-dependent propagation effects are derived.

Plasma eigenmodes become linearly polarized at higher temperatures than previously thought.

Fitting formulas for high-temperature regimes are provided.

Abstract

The transfer of polarized radiation in magnetized and non-magnetized relativistic plasmas is an area of research with numerous flaws and gaps. The present paper is aimed at filling some gaps and eliminating the flaws. Starting from a Trubnikov's linear response tensor for a vacuum wave with ${\bf k}=\omega/c$ in thermal plasma, the analytic expression for the dielectric tensor is found in the limit of high frequencies. The Faraday rotation and Faraday conversion measures are computed in their first orders in the ratio of the cyclotron frequency $\Omega_0$ to the observed frequency $\omega$. The computed temperature dependencies of propagation effects bridge the known non-relativistic and ultra-relativistic limiting formulas. The fitting expressions are found for high temperatures, where the higher orders in $\Omega_0/\omega$ cannot be neglected. The plasma eigenmodes are found to become linearly polarized at much larger temperatures than thought before. The results are applied to the diagnostics of the hot ISM, hot accretion flows, and jets.