Gravitational Larmor precession

TL;DR

This paper introduces the concept of gravitational Larmor precession, a magnetic field-induced precession effect near non-rotating black holes, expanding understanding beyond the traditional rotating black hole models.

Contribution

It demonstrates that magnetic fields alone can cause nodal-plane precession in non-rotating black hole spacetimes, a novel insight in black hole physics.

Findings

Precession frequency is non-zero in magnetized, non-rotating black hole spacetimes.

Magnetic fields can induce precession without black hole rotation.

Potential observational signatures discussed for supermassive black holes.

Abstract

Inspired by the reported existence of substantive magnetic fields in the vicinity of the central supermassive black holes in Sagitarius A* and Messier 87*, we consider test particle motion in the spacetime close to a generic spherical black hole in the presence of magnetic fields in its vicinity. Modelling such a spacetime in terms of an axisymmetric, non-rotating Ernst-Melvin-Schwarzschild black hole geometry with appropriate parameters, we compute the geodesic nodal-plane precession frequency for a test particle with mass, for such a spacetime, and obtain a non-vanishing result, surpassing earlier folklore that only axisymmetric spacetimes with rotation (non-vanishing Kerr parameter) can generate such a precession. We call this magnetic field-generated phenomenon Gravitational Larmor Precession. What we present here is a Proof of Concept incipient assay, rather than a detailed analysis of supermassive black holes with magnetic fields in their neighbourhood. However, for completeness, we briefly discuss observational prospects of this precession in terms of available magnetic field strengths close to central black holes in galaxies.