Generalization of the KKW Analysis for Black Hole Radiation

TL;DR

This paper extends the KKW analysis to non-Schwarzschild black holes, deriving new temperature and entropy expressions, and applies it to the GHS black hole, revealing novel thermodynamic properties and stability features.

Contribution

It introduces a generalized coordinate transformation for non-Schwarzschild black holes in the KKW framework, enabling analysis of their Hawking radiation and thermodynamics.

Findings

Derived temperature and entropy for non-Schwarzschild black holes.

Found extremal GHS black hole has a non-zero temperature.

Modified extremality condition prevents naked singularities.

Abstract

An extension of the Keski-Vakuri, Kraus and Wilczek (KKW) analysis to black hole spacetimes which are not Schwarzschild-type is presented. Preserving the regularity at the horizon and stationarity of the metric in order to deal with the across-horizon physics, a more general coordinate transformation is introduced. In this analysis the Hawking radiation is viewed as a tunnelling process which emanates from the non-Schwarzschild-type black hole. Expressions for the temperature and entropy of these non-Schwarzschild-type black holes are extracted. As a paradigm, in the context of this generalization, we consider the Garfinkle-Horowitz-Strominger (GHS) black hole as a dynamical background and we derive the modified temperature and entropy of GHS black hole. Deviations are eliminated and corresponding standard results are recovered to the lowest order in the emitted shell of energy. The extremal GHS black hole is found to be non-``frozen'' since it is characterized by a constant non-zero temperature. Furthermore, the modified extremality condition forbids naked singularities to form from the collapse of the GHS black hole.