Tachyon Hair on Two-Dimensional Black Holes

TL;DR

This paper investigates the presence and properties of tachyon hair on two-dimensional black holes in string theory, analyzing static and dynamical solutions and their implications for black hole formation and evolution.

Contribution

It introduces new static and dynamical solutions for tachyon hair on 2D black holes and discusses their stability and physical relevance.

Findings

Non-singular solutions have non-vanishing asymptotic energy density.

Black holes formed in collapse lack tachyon hair.

Static solutions with finite energy can have singular horizons.

Abstract

Static black holes in two-dimensional string theory can carry tachyon hair. Configurations which are non-singular at the event horizon have non-vanishing asymptotic energy density. Such solutions can be smoothly extended through the event horizon and have non-vanishing energy flux emerging from the past singularity. Dynamical processes will not change the amount of tachyon hair on a black hole. In particular, there will be no tachyon hair on a black hole formed in gravitational collapse if the initial geometry is the linear dilaton vacuum. There also exist static solutions with finite total energy, which have singular event horizons. Simple dynamical arguments suggest that black holes formed in gravitational collapse will not have tachyon hair of this type.