Magnetic neutral points and electric lines of force in strong gravity of a rotating black hole

TL;DR

This paper investigates how strong gravity near a rotating black hole can create magnetic null points and electric fields, potentially leading to efficient particle acceleration and magnetic reconnection in galactic nuclei.

Contribution

It demonstrates that purely geometrical effects of strong gravity and frame-dragging can generate magnetic null points near Kerr black holes, influencing particle acceleration.

Findings

Magnetic null points can form near rotating black holes due to gravitational effects.

Magnetic reconnection sites may be located at these null points.

Particles can be accelerated efficiently by electric fields in these regions.

Abstract

Magnetic field can be amplified and twisted near a supermassive black hole residing in a galactic nucleus. At the same time magnetic null points develop near the horizon. We examine a large-scale oblique magnetic field near a rotating (Kerr) black hole as an origin of magnetic layers, where the field direction changes abruptly in the ergosphere region. In consequence of this, magnetic null points can develop by purely geometrical effects of the strong gravitational field and the frame-dragging mechanism. We identify magnetic nulls as possible sites of magnetic reconnection and suggest that particles may be accelerated efficiently by the electric component. The situation we discuss is relevant for starving nuclei of some galaxies which exhibit episodic accretion events, namely, Sagittarius A* black hole in our Galaxy.