Destroying extremal magnetized black holes

TL;DR

This paper investigates whether extremal magnetized black holes can be destroyed by test particles, finding that magnetic fields prevent particles from reaching the horizon despite having enough energy.

Contribution

It extends Wald's thought experiment to magnetized black holes, revealing magnetic fields' role in preventing black hole destruction.

Findings

External magnetic fields enable test particles to have enough energy to destroy the black hole.

Effective potential analysis shows particles cannot reach the horizon due to magnetic effects.

Magnetic fields act as a protective mechanism against black hole destruction.

Abstract

The gedanken experiment by Wald to destroy a black hole using a test particle in the equatorial plane is adopted to the case of extremal magnetized black holes. We find the presence of external magnetic fields resulting from the "Ernst magnetization" permits a test particle to have strong enough energy to destroy the black hole. However, the corresponding effective potentials show that such particles would never reach the horizon.