Excitation factors and exceptional points of Kerr-de Sitter quasinormal modes
Abstract
We compute the excitation factors of Kerr-de Sitter black hole quasinormal modes using two different techniques: a Heun function representation and an expansion of the solution in terms of hypergeometric functions. Exceptional points at which the complex frequencies of different overtones coincide are a generic feature of the Kerr-de Sitter quasinormal mode spectrum. Near exceptional points, the modes exhibit a "hysteresis phenomenon" that was previously found for Kerr black holes perturbed by massive fields and the absolute value of the excitation factors of the individual modes is significantly enhanced, while they acquire nearly opposite phases. We extrapolate the excitation factors to small values of the cosmological constant and find good agreement with previous calculations in the Kerr limit.
Related
- Excitation factors and exceptional points of Kerr--Newman quasinormal modes
- Quasinormal-mode encounters: Pseudospectra near Kerr--Newman exceptional points
- Quasinormal frequencies and greybody factors for axial perturbations of dilaton-Euler-Heisenberg de Sitter black holes
- Nonoscillatory gravitational quasinormal modes of Reissner–Nordström–de Sitter spacetime
- Quasinormal modes of Kerr-Newman-de Sitter black holes from Heun connection formulae
BibTeX
@misc{rossi2026excitation,
title = {{Excitation factors and exceptional points of Kerr-de Sitter quasinormal modes}},
author = {Dario Rossi and Naritaka Oshita and Leonardo Gualtieri and Emanuele Berti},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.03009},
eprint = {2609.03009},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.03009},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Excitation factors and exceptional points of Kerr-de Sitter quasinormal modes
AU - Dario Rossi
AU - Naritaka Oshita
AU - Leonardo Gualtieri
AU - Emanuele Berti
PY - 2026
DA - 2026/09/02
PB - arXiv
DO - 10.48550/arxiv.2609.03009
UR - https://arxiv.org/abs/2609.03009
AB - We compute the excitation factors of Kerr-de Sitter black hole quasinormal modes using two different techniques: a Heun function representation and an expansion of the solution in terms of hypergeometric functions. Exceptional points at which the complex frequencies of different overtones coincide are a generic feature of the Kerr-de Sitter quasinormal mode spectrum. Near exceptional points, the modes exhibit a "hysteresis phenomenon" that was previously found for Kerr black holes perturbed by massive fields and the absolute value of the excitation factors of the individual modes is significantly enhanced, while they acquire nearly opposite phases. We extrapolate the excitation factors to small values of the cosmological constant and find good agreement with previous calculations in the Kerr limit.
ER -