The physics of non-ideal general relativistic magnetohydrodynamics

TL;DR

This paper develops a comprehensive framework for non-ideal relativistic magnetohydrodynamics, linking microphysical processes with global dynamics, and discusses assumptions like charge neutrality relevant for astrophysical simulations.

Contribution

It introduces a consistent formulation of non-ideal GRMHD that incorporates microphysics and examines key assumptions affecting astrophysical modeling.

Findings

Highlights the importance of microphysics in global dynamics.

Analyzes the assumptions behind ideal and resistive MHD.

Prepares groundwork for advanced astrophysical simulations.

Abstract

We consider a framework for non-ideal magnetohydrodynamics in general relativity, paying particular attention to the physics involved. The discussion highlights the connection between the microphysics (associated with a given equation of state) and the global dynamics (from the point of view of numerical simulations), and includes a careful consideration of the assumptions that lead to ideal and resistive magnetohydrodynamics. We pay particular attention to the issue of local charge neutrality, which tends to be assumed but appears to be more involved than is generally appreciated. While we do not resolve all the involved issues, we highlight how some of the assumptions and simplifications may be tested by simulations. The final formulation is consistent, both logically and physically, preparing the ground for a new generation of models of relevant astrophysical scenarios.