# String analog of Reissner-Nordstr\"om black holes cannot be overcharged

## TL;DR

This paper demonstrates that string theory black holes analogous to Reissner-Nordström cannot be overcharged, supporting the third law of black hole thermodynamics even in string theory contexts.

## Contribution

It shows that extremal and nearly extremal Garfinkle-Horowitz-Strominger black holes cannot be overcharged, extending the third law of black hole thermodynamics to string theory black holes.

## Key findings

- Extremal black holes cannot be overcharged.
- Nearly extremal black holes cannot be driven to extremality.
- Supports the third law of black hole thermodynamics in string theory.

## Abstract

In this work we attempt to overcharge extremal and nearly extremal charged black holes in string theory, known as the Garfinkle-Horowitz-Strominger solution. We first show that extremal black holes cannot be overcharged analogous to the case of Reissner-Nordstr\"{o}m black holes. Contrary to their analogues in general relativity, nearly extremal black holes can neither be overcharged beyond extremality, nor can they be driven to extremality by the interaction with test particles. Therefore the analysis in this work also imply that the third law of black hole thermodynamics holds for the relevant charged black holes in string theory perturbed by test particles. This can be interpreted as a stronger version of the third law since one can drop out the continuity proviso for the relevant process.