Hawking radiation, the Stefan-Boltzmann law, and unitarization

TL;DR

This paper investigates the origin of Hawking radiation, arguing it arises from a near-horizon quantum atmosphere, and discusses implications for unitarity restoration and black hole thermodynamics.

Contribution

It challenges the common near-horizon excitation picture by showing the radiation source is a quantum atmosphere with a scale set by the horizon radius.

Findings

Hawking radiation originates from a near-horizon quantum atmosphere.

The scale of this atmosphere is comparable to the horizon radius.

Implications for unitarity and black hole thermodynamics are discussed.

Abstract

Where does Hawking radiation originate? A common picture is that it arises from excitations very near or at the horizon, and this viewpoint has supported the "firewall" argument and arguments for a key role for the UV-dependent entanglement entropy in describing the quantum mechanics of black holes. However, closer investigation of both the total emission rate and the stress tensor of Hawking radiation supports the statement that its source is a near-horizon quantum region, or "atmosphere," whose radial extent is set by the horizon radius scale. This is potentially important, since Hawking radiation needs to be modified to restore unitarity, and a natural assumption is that the scales relevant to such modifications are comparable to those governing the Hawking radiation. Moreover, related discussion suggests a resolution to questions regarding extra energy flux in "nonviolent" scenarios, that does not spoil black hole thermodynamics as governed by the Bekenstein-Hawking entropy.