Evaporation of Two Dimensional Black Holes

TL;DR

This paper examines the semi-classical evaporation process of two-dimensional black holes, revealing potential singularities or breakdowns of approximation as the black hole approaches critical conditions.

Contribution

It analyzes the behavior of two-dimensional black hole models during evaporation, highlighting the limitations of semi-classical equations near critical dilaton values.

Findings

Singularity formation at critical dilaton values

Finite temperature and emission rate during evaporation

Possible breakdown of semi-classical approximation

Abstract

Callan, Giddings, Harvey and Strominger have proposed an interesting two dimensional model theory that allows one to consider black hole evaporation in the semi-classical approximation. They originally hoped the black hole would evaporate completely without a singularity. However, it has been shown that the semi-classical equations will give a singularity where the dilaton field reaches a certain critical value. Initially, it seems this singularity will be hidden inside a black hole. However, as the evaporation proceeds, the dilaton field on the horizon will approach the critical value but the temperature and rate of emission will remain finite. These results indicate either that there is a naked singularity, or (more likely) that the semi-classical approximation breaks down when the dilaton field approaches the critical value.