Absorption of a Particle by a Rotating Black Hole: The Potential Barrier

TL;DR

This paper investigates how particles can be absorbed by rapidly rotating black holes, revealing conditions where the black hole's horizon persists but its area decreases, challenging Hawking's area theorem.

Contribution

It demonstrates that under certain conditions, test particles can reduce a black hole's area, suggesting limitations of the test particle approximation in black hole physics.

Findings

Particles can reach the horizon with specific energy and angular momentum.

Absorption can decrease the black hole's area, violating Hawking's theorem.

Test particle approximation may cause the apparent violation.

Abstract

For a test particle approaching a rapidly rotating black hole we find a range of values of the particle's energy and angular momentum, on the order of 1\% or more of the corresponding values of the hole, such that three conditions are satisfied. 1) The particle can reach the horizon. 2) After absorption the new hole still has a horizon. 3) The area of the new hole is less than the area of the original one, in apparent violation of a theorem of Hawking. We offer support for the claim that the test particle approximation is the cause of the violation.