Delicate windows into evaporating black holes

TL;DR

This paper investigates how information about an evaporating AdS$_2$ black hole can be retrieved from Hawking radiation, analyzing phase transitions, entropy evolution, and complexity to understand interior access over time.

Contribution

It refines the understanding of island phase transitions and interior access for finite radiation segments, including the effects of the purifier and parameter sensitivity.

Findings

Established island phase transition for semi-infinite radiation segments.

Identified four entropy evolution scenarios for finite radiation segments.

Analyzed the sensitivity of the Page curve to model parameters.

Abstract

We revisit the model of an AdS$_2$ black hole in JT gravity evaporating into an external bath. We study when, and how much, information about the black hole interior can be accessed through different portions of the Hawking radiation collected in the bath, and we obtain the corresponding full quantitative Page curves. As a refinement of previous results, we describe the island phase transition for a semi-infinite segment of radiation in the bath, establishing access to the interior for times within the regime of applicability of the model. For finite-size segments in the bath, one needs to include the purifier of the black hole microscopic dual together with the radiation segment in order to access the interior information. We identify four scenarios of the entropy evolution in this case, including a possibility where the interior reconstruction window is temporarily interrupted. Analyzing the phase structure of the Page curve of a finite segment with length comparable to the Page time, we demonstrate that it is very sensitive to changes of the parameters of the model. We also discuss the evolution of the subregion complexity of the radiation during the black hole evaporation.