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Main Author: Hohenegger, Stefan
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.17781
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author Hohenegger, Stefan
author_facet Hohenegger, Stefan
contents In recent works, a framework has been developed to describe (quantum) deformed, spherically symmetric and static black holes in four dimensions. The key idea of this so-called Effective Metric Description (EMD) is to parametrise deformations of the classical Schwarzschild geometry by two functions that depend on a physical quantity and which are calculated in a self-consistent way as series expansions in the vicinity of the horizon. In this work we further strengthen this framework by first demonstrating that the corresponding series expansion coefficients can be completely and uniquely determined from measurements that are accessible for observers outside of the event horizon: we propose a Gedankenexperiment, consisting of probes following a free-falling trajectory that send signals to a stationary observer and show how an EMD can be constructed from suitable telemetric data. Furthermore, by linking the expansion coefficients of the EMD to the invariant eigenvalues of the energy momentum tensor, we determine a system of physical fields that provides an effective Einstein equation for the deformed black hole geometry. In the case of a simplified geometry and assuming that the metric deformations are small, we can write the leading order of the physical fields in a closed form in the metric functions. We illustrate our results at the example of the Hayward space-time.
format Preprint
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institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Probing Effective Black Hole Deformations
Hohenegger, Stefan
General Relativity and Quantum Cosmology
High Energy Physics - Theory
In recent works, a framework has been developed to describe (quantum) deformed, spherically symmetric and static black holes in four dimensions. The key idea of this so-called Effective Metric Description (EMD) is to parametrise deformations of the classical Schwarzschild geometry by two functions that depend on a physical quantity and which are calculated in a self-consistent way as series expansions in the vicinity of the horizon. In this work we further strengthen this framework by first demonstrating that the corresponding series expansion coefficients can be completely and uniquely determined from measurements that are accessible for observers outside of the event horizon: we propose a Gedankenexperiment, consisting of probes following a free-falling trajectory that send signals to a stationary observer and show how an EMD can be constructed from suitable telemetric data. Furthermore, by linking the expansion coefficients of the EMD to the invariant eigenvalues of the energy momentum tensor, we determine a system of physical fields that provides an effective Einstein equation for the deformed black hole geometry. In the case of a simplified geometry and assuming that the metric deformations are small, we can write the leading order of the physical fields in a closed form in the metric functions. We illustrate our results at the example of the Hayward space-time.
title Probing Effective Black Hole Deformations
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2508.17781