Numerical Treatment of Anisotropic Radiation Field Coupling with the Relativistic Resistive Magnetofluids

TL;DR

This paper presents a novel numerical scheme for relativistic resistive radiation magnetohydrodynamics that accurately models anisotropic radiation fields and includes radiation-magnetic interactions, validated through various tests and applications.

Contribution

The authors develop a comprehensive numerical method that combines M-1 closure for radiation, explicit advection, and implicit source term integration for relativistic resistive MHD.

Findings

The scheme conserves mass, momentum, and energy effectively.

It accurately resolves anisotropic radiation fields.

Application to magnetic reconnection shows radiation drag reduces reconnection rate.

Abstract

We develop a numerical scheme for solving a fully special relativistic resistive radiation magnetohydrodynamics. Our code guarantees conservations of total mass, momentum and energy. Radiation energy density and radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation fields in contrast to the Eddington approximation as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of the Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly HLL scheme, and HLLC and HLLD schemes for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in optically thick regime or a large magnetic Reynolds number regime. Although we need to invert $4\times 4$ (for gas-radiation interaction) and $3\times 3$ (for magnetic energy dissipation) matrices at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek type magnetic reconnection, revealing the reduction of the reconnection rate via the radiation drag.