Cosmic Censorship, Black Holes and Integer-spin Test Fields

TL;DR

This paper demonstrates that extremal Kerr black holes cannot be overspun by massless integer-spin test fields, but nearly extremal black holes can be, highlighting limits of the cosmic censorship conjecture under idealized conditions.

Contribution

It shows that extremal Kerr black holes are resistant to overspinning by massless integer-spin fields, extending the analysis to more general black holes and field configurations.

Findings

Extremal Kerr black holes cannot be overspun by massless integer-spin test fields.

Overspinning is possible starting from nearly extremal black holes.

Results apply to scalar fields and more general black holes, neglecting radiative and self-force effects.

Abstract

It has been argued that, starting with a slightly sub-extremal Kerr black hole instead of an extremal one, it is possible to overspin a black hole past the extremal limit and turn it into a naked singularity by sending test bodies, if one neglects radiative and self-force effects. In this work we show that (i) an extremal Kerr black hole can not be overspun as a result of the interaction with massless integer spin test fields (scalar, electromagnetic, or gravitational), (ii) overspinning can be achieved if we start with a nearly extremal black hole instead, and (iii) for the scalar field, the argument applies to more general black holes, and also allows use of a more general field configuration. Our analysis also neglects radiative and self-force effects.