Semi-infinite Throat as the End-state Geometry of two-dimensional Black Hole Evaporation

TL;DR

This paper investigates a solvable two-dimensional dilaton gravity model showing black hole formation and evaporation, culminating in a unique static end-state with a semi-infinite throat, highlighting the end-stage geometry of black hole evaporation.

Contribution

It introduces a modified 2D dilaton gravity model with exact semiclassical solutions, revealing the end-state geometry as a semi-infinite throat after evaporation.

Findings

Black holes form when infalling matter exceeds a threshold.

Evaporating black holes develop a naked singularity at the end of evaporation.

The end-state geometry features a semi-infinite throat extending into strong coupling.

Abstract

We study a modified two-dimensional dilaton gravity theory which is exactly solvable in the semiclassical approximation including back-reaction. The vacuum solutions of this modified theory are asymptotically flat static space-times. Infalling matter forms a black hole if its energy is above a certain threshold. The black hole singularity is initially hidden behind a timelike apparent horizon. As the black hole evaporates by emitting Hawking radiation, the singularity meets the shrinking horizon in finite retarded time to become naked. A natural boundary condition exists at the naked singularity such that for general infalling matter-configuration the evaporating black hole geometries can be matched continuously to a unique static end-state geometry. This end-state geometry is asymptotically flat at its right spatial infinity, while its left spatial infinity is a semi-infinite throat extending into the strong coupling region.