Travelling Magnetic Waves due to Plasma Surrounding a Slow Rotating Compact Gravitational Source

TL;DR

This paper investigates magnetic waves generated by plasma around a slowly rotating black hole, revealing that spacetime dragging induces azimuthal magnetic waves traveling at the frame's angular velocity.

Contribution

It provides exact solutions for magnetic fields in plasma near a slow rotating black hole, highlighting the role of spacetime dragging in magnetic wave induction.

Findings

Magnetic waves travel along azimuthal direction with the frame's angular velocity.

Spacetime dragging induces magnetic fields at fixed azimuthal angles.

Solutions apply to various astrophysical plasma scenarios.

Abstract

The magnetic field due to an axially symmetric, hot and highly conducting plasma, taken as an ideal magnetohydrodynamic fluid, surrounding a slow rotating compact gravitational object is studied within the context of Einstein-Maxwell field equations. It is assumed that whereas the plasma is effected by the background spacetime it does not effect the spacetime itself. The Einstein-Maxwell equations are then solved for the magnetic field in a comoving frame with the background spacetime described by the slow rotating Kerr black hole spacetime. It is found that the solutions are magnetic waves travelling along the azimuthal angle with velocity equal to the angular velocity of a free falling intertial frame. These general solutions, when applied to various particular cases of physical interest, show that for a fixed value of the azimuthal angle the magnetic field is completely induced by the dragging of the background spacetime.