Fiducial observers and the thermal atmosphere in the black hole quantum throat

TL;DR

This paper constructs fiducial observers in the near-horizon region of near-extremal black holes within JT quantum gravity, linking geometric dressing with quantum gravitational effects and wormhole contributions.

Contribution

It introduces a unique construction of local observers in a highly quantum black hole regime, connecting conformal isometries with modular flow and quantum gravitational observables.

Findings

Computed quantum gravitational wormhole contributions to the black hole thermal atmosphere.

Produced a finite thermal entropy for the black hole.

Provided a quantum description of the stretched horizon.

Abstract

We propose a construction of fiducial observers in the throat region of near-extremal black holes within the framework of JT quantum gravity, leading to a notion of local observers in a highly quantum regime of the gravitational field. The construction is based on an earlier proposal for light-ray anchoring to the asymptotic boundary and is uniquely fixed at the semiclassical level by demanding that the notion of time translations for an observer at the asymptotic boundary of JT gravity should be extended into the bulk as the flow of a conformal isometry. Since conformal isometries are a necessary condition for geometric modular flow, our construction is amenable as a candidate geometric gravitational dressing that may be interpreted via the modular crossed product, potentially connecting our choice of dressing with recent developments on the literature on local observables in quantum gravity. Taking this definition beyond the semiclassical regime, we compute quantum gravitational wormhole contributions to the black hole thermal atmosphere, directly producing a finite thermal entropy and leading to a quantum description of the stretched horizon in this model.