New perspectives on Hawking radiation

TL;DR

This paper introduces an adiabatic formalism to analyze Hawking radiation from non-stationary detector trajectories, revealing new insights into temperature perception and mode excitation near black holes.

Contribution

It develops a novel adiabatic approach to study Hawking radiation from non-stationary trajectories, highlighting effects on detector temperature and mode excitation.

Findings

Detectors on circular orbits perceive higher temperatures than static ones.

Infalling detectors can experience diverging energy flux near the horizon.

High binding energy infalling trajectories dominate mode excitation close to the horizon.

Abstract

We develop an adiabatic formalism to study the Hawking phenomenon from the perspective of Unruh-DeWitt detectors moving along non-stationary, non-asymptotic trajectories. When applied to geodesic trajectories, this formalism yields the following results: (i) though they have zero acceleration, the temperature measured by detectors on circular orbits is higher than that measured by static detectors at the same distance from the hole, and diverges on the photon sphere, (ii) in the near-horizon region, both outgoing and incoming modes excite infalling detectors, and, for highly bound trajectories (E<<1), the latter actually dominate the former. We confirm the apparent perception of high-temperature Hawking radiation by infalling observers with E<<1 by showing that the energy flux measured by these observers diverges in the E->0 limit. We close by a discussion of the role played by spacetime curvature on near-horizon Hawking radiation.