Quantum kinetics and prethermalization of Hawking radiation

TL;DR

This paper explores the quantum dynamics of Hawking radiation during black hole formation, revealing a family of out-vacua that encode initial state memory and may offer insights into the information loss paradox.

Contribution

It demonstrates the existence of a multi-parametric family of out-vacua in black hole formation, linking initial conditions to the final quantum state and addressing the information paradox.

Findings

Multiple out-vacua exist during collapse.

Initial conditions influence the final vacuum state.

A thermal vacuum state can form, potentially resolving the paradox.

Abstract

We reinvestigate the emission of Hawking radiation during gravitational collapse to a black hole. Both CGHS collapse of a shock wave in (1+1)-dimensional dilaton gravity and Schwarzschild collapse of a spherically symmetric thin shell in (3+1)-dimensional gravity are considered. Studying the dynamics of in-vacuum polarization, we find that a multi-parametric family of out-vacua exists. Initial conditions for the collapse lead dynamically to different vacua from this family as the final state. Therefore, the form of the out-vacuum encodes memory about the initial quantum state of the system. While most out-vacua feature a non-thermal Hawking flux and are expected to decay quickly, there also exists a thermal vacuum state. Collectively, these observations suggest an interesting possible resolution of the information loss paradox.