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Main Authors: Xiong, Wei, Li, Peng-Cheng
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.08557
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author Xiong, Wei
Li, Peng-Cheng
author_facet Xiong, Wei
Li, Peng-Cheng
contents Recently, significant progress has been made in the study of black hole (BH) perturbations, both within the framework of general modified gravity theories and in complex environments. However, a well-established conclusion regarding the boundary conditions of the perturbed fields remains elusive. In this paper, we investigate the boundary conditions for a general perturbation at spatial infinity and the event horizon of a black hole (BH) described by a generic metric that is stationary, axisymmetric, asymptotically flat, and respects the condition of circularity. Our analysis is independent of any specific BH model or the nature of the perturbed field. In particular, by extending the formulation introduced by Teukolsky and utilizing purely geometric principles, we derive a universal expression for the boundary condition at the horizon. This expression is elegantly formulated in terms of the physical quantities at the event horizon, specifically the BH's surface gravity and angular velocity. The results presented in this work may provide valuable insights for the calculation of quasinormal modes and the gravitational waves generated by extreme-mass-ratio inspirals, extending beyond the standard Kerr case.
format Preprint
id arxiv_https___arxiv_org_abs_2501_08557
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Boundary conditions of general black hole perturbations
Xiong, Wei
Li, Peng-Cheng
General Relativity and Quantum Cosmology
Recently, significant progress has been made in the study of black hole (BH) perturbations, both within the framework of general modified gravity theories and in complex environments. However, a well-established conclusion regarding the boundary conditions of the perturbed fields remains elusive. In this paper, we investigate the boundary conditions for a general perturbation at spatial infinity and the event horizon of a black hole (BH) described by a generic metric that is stationary, axisymmetric, asymptotically flat, and respects the condition of circularity. Our analysis is independent of any specific BH model or the nature of the perturbed field. In particular, by extending the formulation introduced by Teukolsky and utilizing purely geometric principles, we derive a universal expression for the boundary condition at the horizon. This expression is elegantly formulated in terms of the physical quantities at the event horizon, specifically the BH's surface gravity and angular velocity. The results presented in this work may provide valuable insights for the calculation of quasinormal modes and the gravitational waves generated by extreme-mass-ratio inspirals, extending beyond the standard Kerr case.
title Boundary conditions of general black hole perturbations
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2501.08557