Revisiting near-extremal and near-BPS black holes in AdS3 supergravity

TL;DR

This paper analyzes the quantum behavior of near-extremal and near-BPS black holes in AdS3 supergravity, revealing differences in the gravitational path integral at low temperatures and clarifying the role of boundary conditions and quantum fluctuations.

Contribution

It systematically investigates quantum fluctuations and boundary conditions in AdS3 supergravity, refining understanding of near-extremal and near-BPS black hole regimes.

Findings

The gravitational path integral near-horizon differs from that around BTZ at low temperature.

Boundary conditions significantly influence quantum fluctuations in AdS3.

Disparities between near-extremal and near-BPS limits are clarified at the quantum level.

Abstract

Despite the archetypal status of the BTZ background in quantifying quantum aspects of black holes, several features at low temperatures remain imprecise and incomplete. Here, we systematically investigate the behaviour of the Euclidean path integral at low temperatures in the context of AdS3 supergravity, including an analysis of quantum fluctuations in both the near-horizon and asymptotic regions. We clarify and rectify aspects of the bosonic fluctuations, highlighting the role of boundary conditions in AdS3, and show in particular that the gravitational path integral in the near-horizon region is inequivalent to that around BTZ at low temperature. We further account in detail for the contributions of Chern-Simons fields and spin-3/2 modes, thereby refining the disparities between the near-extremal and near-BPS limits at low temperature. Altogether, our analysis sharpens the distinction between near- and far-region dynamics and demonstrates a disagreement in the gravitational path integral at the quantum level.