Possible observational windows for quantum effects from black holes

Abstract

Quantum information transfer necessary to reconcile black hole evaporation with quantum mechanics, while approximately preserving regular near-horizon geometry, can be simply parameterized in terms of couplings of the black hole internal state to quantum fields of the black hole atmosphere. The necessity of transferring sufficient information for unitarization sets the strengths of these couplings. Such couplings via the stress tensor offer apparently significant advantages, and behave like quantum fluctuations of the effective metric near the horizon. At the requisite strength, these fluctuations, while soft (low energy/momentum), have significant magnitude, and so can deflect near-horizon geodesics that span distances of order the black hole radius. Thus, the presence of such couplings can result in effects that could be detected or constrained by observation: disruption of near-horizon accretion flows, scintillation of light passing close to the black hole, and alteration of gravitational wave emission from inspirals. These effects could in particular distort features of Sgr A* expected to be observed, e.g., by the Event Horizon Telescope, such as the black hole shadow and photon ring.

15 pages of text + refs; harvmac. v2: added refs. and minor rewordings. v3: added comments, including emphasizing role of photon ring; version accepted by PRD

References in corpus (7)

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• Testing the Kerr metric with the iron line and the KRZ parametrization
• Quantum Gravity Effects around Sagittarius A*
• The Good, the Bad, and the Ugly of Gravity and Information
• Constraining the Kerr parameters via X-ray reflection spectroscopy
• Shining Light on Quantum Gravity with Pulsar-Black Hole Binaries
• Probing the Spacetime Around Supermassive Black Holes with Ejected Plasma Blobs
• Stationary black holes with stringy hair
• Higher-Curvature Gravity, Black Holes and Holography