Investigating the gedanken experiment to destroy the event horizon of a regular black hole

Yunjiao Gao,Jie Jiang

doi:10.1103/physrevd.101.084005

Abstract

Recently, Li and Bambi proposed a hypothesis that the event horizon of a regular black hole can be destroyed because these objects have no gravitational singularity and therefore they are not protected by the weak cosmic censorship conjecture (WCCC). In this paper, to test their hypothesis, we perform the new version of the gedanken experiments proposed by Sorce and Wald to overcharge a near extremal static electrically regular black hole. After introducing the stability condition of the spacetime and the null energy condition of matter fields, we derive the first-order and second-order perturbation inequalities of the perturbation matter fields based on the Iyer-Wald formalism. As a result, we find that these regular black holes cannot be destroyed under the second-order approximation after these two perturbation inequalities are taken into account, even though they are not protected by the WCCC. Our results indicate that there might be some deeper mechanisms to protect the event horizon of the black holes.

Highlights

A gravitational singularity is usually mathematically illdefined which leads to the invalidity of predictability of spacetime
Penrose formulated the weak cosmic censorship conjecture (WCCC) to ensure the causality of the spacetime. This conjecture states that the gravitational singularity must be hidden inside the event horizon such that it will not be detected by distant observers out of the horizon [1]
We performed the new version of the gedanken experiments proposed by Sorce and Wald to overcharge a nearly extremal static electrically regular black hole

Summary

INTRODUCTION

A gravitational singularity is usually mathematically illdefined which leads to the invalidity of predictability of spacetime. To test the validity of this conjecture, Wald proposed a gedanken experiment to see whether the event horizon of an extremal Kerr-Newman (KN) black hole would be destroyed after throwing a test particle into it [2] As a result, they found that the extremal KN black holes cannot be destroyed in this way under the first-order approximation of perturbation [2]. In 2013, Li and Bambi [35] studied the possibility of destroying the event horizon of regular black holes They found that the rotating Bardeen and Hayward black holes can be overspun by throwing a test particle under the second-order approximation. In this paper, to test their hypothesis, we would like to apply the new version of the gendanken experiments to the static electrically regular black holes and investigate whether the event horizon could be destroyed under the second-order approximation.

ELECTRIC REGULAR BLACK HOLE WITH SPHERICAL MATTER COLLISION

PERTURBATION INEQUALITIES

GEDANKEN EXPERIMENTS TO DESTROY THE REGULAR BLACK HOLES

CONCLUSION