Generalized General Relativistic MHD Equations and Distinctive Plasma Dynamics around Rotating Black Holes

TL;DR

This paper develops a 3+1 formalism for generalized GRMHD equations to analyze plasma behaviors near rotating black holes, highlighting effects like gravitation and frame-dragging on plasma dynamics and magnetic reconnection.

Contribution

It introduces a comprehensive 3+1 formalism for generalized GRMHD equations, incorporating relativistic effects and clarifying their applicability in black hole magnetospheres.

Findings

Electromotive forces due to gravity, centrifugal, and frame-dragging effects confirmed.

Conditions for applying different GRMHD models clarified.

Magnetic reconnection potentially triggered by relativistic effects.

Abstract

To study phenomena of plasmas around rotating black holes, we have derived a set of 3+1 formalism of generalized general relativistic magnetohydrodynamic (GRMHD) equations. Especially, we investigated general relativistic phenomena with respect to the Ohm's law. We confirmed the electromotive force due to the gravitation, centrifugal force, and frame-dragging effect in plasmas near the black holes. These effects are significant only in the local small-scale phenomena compared to the scale of astrophysical objects. We discuss the possibility of magnetic reconnection, which is triggered by one of these effects in a small-scale region and influences the plasmas globally. We clarify the conditions of applicability of the generalized GRMHD, standard resistive GRMHD, and ideal GRMHD for plasmas in black hole magnetospheres.