Quantum radiation from a sandwich black hole

TL;DR

This paper analyzes quantum radiation from a nonsingular black hole model with a finite lifetime, showing that for large time intervals the radiation resembles Hawking radiation and exploring the effects of different interior metrics on radiation peaks.

Contribution

It demonstrates that in a sandwich black hole model, quantum radiation closely matches Hawking radiation for large time gaps, and investigates how interior metric modifications affect radiation peaks.

Findings

Radiation after black hole formation aligns with Hawking's prediction for large time intervals.

The interior radiation peak is exponentially large in the standard model but suppressed in the modified metric.

Surface gravity reduction in the modified metric decreases the energy outburst at the inner horizon.

Abstract

We discuss quantum radiation of a massless scalar field from a spherically symmetric nonsingular black hole with finite lifetime. Namely, we discuss a sandwich black-hole model, where a black hole is originally created by a collapse of a null shell of mass $M$, and later, after some time $\Delta V$, it is disrupted by the collapse of the other shell with negative mass $-M$. We assume that between the shells the metric is static and either coincides with the Hayward metric or with a special generalization of it. We show that in both cases for sufficiently large parameter $\Delta V$ the radiation after the formation of the black hole practically coincides with the Hawking result. We also calculated the radiation, emitted from the black hole interior. This radiation contains peak at the moment when the second shell intersects the inner horizon. In the standard sandwich metric (with the Hayward interior) this outburst of the energy is exponentially large. In the modified metric, which includes additional non-trivial redshift parameter, this exponent is suppressed. This is a result of significant decrease of the surface gravity of the inner horizon in the latter case. We discuss possible consequences of this result in context of the self-consistency requirement for nonsingular models with quantum radiation.