Cosmic Censorship and parametrized spinning black-hole geometries

TL;DR

This paper examines whether small deviations from Kerr black holes can be spun-up past the extremal limit, finding that cosmic censorship generally holds but can be violated in special cases.

Contribution

It provides a detailed analysis of the stability of cosmic censorship in parametrized deviations from Kerr black holes, identifying conditions under which it can be violated.

Findings

Cosmic censorship is preserved for generic deviations.

Special geometries can be spun-up past extremality.

The study tests the limits of the conjecture in modified black hole solutions.

Abstract

The ``cosmic censorship conjecture'' asserts that all singularities arising from gravitational collapse are hidden within black holes. We investigate this conjecture in a setup of interest for tests of General Relativity: black hole solutions which are parametrically small deviations away from the Kerr solution. These solutions have an upper bound on rotation, beyond which a naked singularity is visible to outside observers. We study whether these (generic) spacetimes can be spun-up past extremality with point particles or accretion disks. Our results show that cosmic censorship is preserved for generic parameterizations. We also present examples of special geometries which can be spun-up past extremality.