A silence black hole: Hawking radiation at the Hagedorn temperature

TL;DR

This paper analyzes Hawking radiation in string theory black holes, showing that emission is exactly thermal and non-unitary, which implies information loss, consistent with string theory predictions.

Contribution

It provides a semi-classical computation of Hawking radiation for various black holes in string theory, revealing thermal emission and non-unitarity even with back-reaction.

Findings

Emission is exactly thermal in the near horizon limit.

Theories are non-unitary and do not preserve information.

The behavior aligns with string theory expectations.

Abstract

We compute semi-classically the Hawking emission for different types of black hole in type II string theory. In particular we analyze the thermal transition between NS5 branes and Little String Theory, finding compelling evidence for information recovering. We find that once the near horizon limit is taken the emission of a full family of models is exactly thermal even if back-reaction is taken into account. Consequently these theories are non-unitary and can not convey any information about the black hole internal states. It is argue that this behaviour matches the string theory expectations. We suggest a plausible reason for the vanishing of the jet-quenching parameter in such theories.