Hawking temperature of black holes with multiple horizons

TL;DR

This paper investigates the Hawking temperature of black holes with multiple horizons, showing that each horizon contributes to the temperature and deriving effective temperatures for specific black hole types.

Contribution

It introduces a method to compute Hawking temperature considering all horizons in multi-horizon spacetimes, extending understanding beyond single-horizon cases.

Findings

Each horizon contributes to the Hawking temperature.

Effective temperature depends on black hole parameters.

Different black holes have distinct temperature dependencies.

Abstract

There are several well-established methods for computing thermodynamics in single-horizon spacetimes. However, understanding thermodynamics becomes particularly important when dealing with spacetimes with multiple horizons. Multiple horizons raise questions about the existence of a global temperature for such spacetimes. Recent studies highlight the significant role played by the contribution of all the horizons in determining Hawking temperature. Here we explore the Hawking temperature of a rotating and charged black hole in four spacetime dimensions and a rotating BTZ black hole. We also find that each horizon of those black holes contributes to the Hawking temperature. The effective Hawking temperature for a four-dimensional rotating and charged black hole depends only on its mass. This temperature is the same as the Hawking temperature of a Schwarzschild black hole. In contrast, the effective Hawking temperature depends on the black hole mass and angular momentum for a rotating BTZ hole.