Temperatures of extremal black holes

TL;DR

This paper explores the temperature properties of extremal black holes, demonstrating that their temperature can be arbitrary and is not constrained by conical singularity considerations, including stringy extremal black holes.

Contribution

It shows how to construct Kruskal-like coordinates for extremal black holes at any temperature, challenging previous assumptions about their temperature restrictions.

Findings

Extremal black holes can have any temperature without conical singularity constraints.

Kruskal-like coordinates can be constructed for arbitrary temperatures.

Stringy extremal black holes also exhibit unrestricted temperature.

Abstract

The temperature of an extremal Reissner - Nordstrom black hole is not restricted by the requirement of absence of a conical singularity. It is demonstrated how Kruskal-like coordinates may be constructed corresponding to any temperature whatsoever. A recently discovered stringy extremal black hole which apparently has an infinite temperature is also shown to have its temperature unrestricted by conical singularity arguments.