Destroying Kerr-Sen black holes

TL;DR

This paper investigates whether near-extremal Kerr-Sen black holes can be destroyed by test particles, potentially violating the extremal bound, extending previous work on Kerr-Newman black holes to string theory contexts.

Contribution

It applies Wald's gedanken experiment to Kerr-Sen black holes, demonstrating the possibility of violating extremality bounds in string theory black holes.

Findings

Feeding test particles can lead to extremal bound violation.

Kerr-Sen black holes may be destroyed similarly to Kerr-Newman black holes.

Results suggest potential instability in string theory black holes.

Abstract

By neglecting the self-force, self-energy, and radiative effects, it has been shown that an extremal or near-extremal Kerr-Newman black hole can turn into a naked singularity when it captures charged and spinning massive particles. A straightforward question then arises: do charged and rotating black holes in string theory possess the same property? In this paper we apply the Wald's gedanken experiment, in his study on the possibility of destroying extremal Kerr-Newman black holes, to the case of (near-)extremal Kerr-Sen black holes. We find that feeding a test particle into a (near-)extremal Kerr-Sen black hole could lead to a violation of the extremal bound for the black hole.