Blushift of a tachyon in the charged 2D black hole

TL;DR

This paper investigates how string fields, especially the tachyon, behave in a 2D charged black hole, revealing the tachyon's propagation and the inner horizon's instability due to infinite blueshift.

Contribution

It demonstrates the propagation of the tachyon in a 2D charged black hole and confirms the inner horizon's instability caused by blueshift effects.

Findings

Tachyon propagates inside and outside the black hole

Inner horizon is unstable due to infinite blueshift

Outer horizon remains stable

Abstract

We study the propagation of string fields (metric $G_{\mu\nu}$, Mawxell gauge potential $A_{\mu}$, dilaton $\Phi$, and tachyon $T$) in a two-dimensional (2D) charged black hole. It is shown that the tachyon is a propagating field both inside and outside the black hole. This becomes infinitely blueshifted at the inner horizon. We confirm that the inner horizon is unstable, whereas the outer horizon is stable.