Magnetized black hole as a gravitational lens

TL;DR

This paper investigates how magnetic fields near black holes and in galaxies influence gravitational lensing, showing that magnetic fields increase light bending and time delays.

Contribution

It introduces corrections to gravitational lensing calculations considering magnetic fields using the Ernst-Schwarzschild solution, highlighting effects near supermassive black holes.

Findings

Magnetic fields increase the bending angle of light.

Magnetic fields cause longer time delays in light propagation.

Effects are significant near supermassive black holes.

Abstract

We use the Ernst-Schwarzschild solution for a black hole immersed in a uniform magnetic field to estimate corrections to the bending angle and time delay due-to presence of weak magnetic fields in galaxies and between galaxies, and also due-to influence of strong magnetic field near supermassive black holes. The magnetic field creates a kind of confinement in space, that leads to increasing of the bending angle and time delay for a ray of light propagating in the equatorial plane.