Numerical Evaluation of the Relativistic Magnetized Plasma Susceptibility Tensor and Faraday Rotation Coefficients

TL;DR

This paper presents a new general method for calculating absorption and Faraday rotation coefficients in relativistic plasmas using the plasma susceptibility tensor, applicable to arbitrary isotropic electron distributions, with implementation in an accessible software library.

Contribution

It introduces a comprehensive procedure for computing plasma coefficients for any isotropic distribution, expanding beyond previous specific cases, and provides a software tool for practical use.

Findings

Validated the method against known results for specific distributions.

Provided a publicly available library for easy implementation.

Offered detailed comparisons with earlier approaches.

Abstract

Polarized models of relativistically hot astrophysical plasmas require transport coefficients as input: synchrotron absorption and emission coefficients in each of the four Stokes parameters, as well as three Faraday rotation coefficients. Approximations are known for all coefficients for a small set of electron distribution functions, such as the Maxwell-Juttner relativistic thermal distribution, and a general procedure has been obtained by Huang & Shcherbakov for an isotropic distribution function. Here we provide an alternative general procedure, with a full derivation, for calculating absorption and rotation coefficients for an arbitrary isotropic distribution function. Our method involves the computation of the full plasma susceptibility tensor, which in addition to absorption and rotation coefficients may be used to determine plasma modes and the dispersion relation. We implement the scheme in a publicly available library with a simple interface, thus allowing for easy incorporation into radiation transport codes. We also provide a comprehensive survey of the literature and comparison with earlier results.