Quasinormal modes and continuum response of de Sitter black holes via complex scaling method
Abstract
We apply the complex scaling method to black-hole perturbations in four-dimensional Schwarzschild--de~Sitter (dS) spacetimes. The method converts the outgoing-wave boundary-value problem into a non-Hermitian spectral problem and enables quasinormal-mode poles and the rotated continuum to be treated in a common framework. We focus in particular on the continuum level density, which characterizes the continuum response beyond isolated quasinormal-mode frequencies. Using Regge--Wheeler-type perturbation equations for scalar, electromagnetic, and gravitational fields, we investigate how a nonzero cosmological constant modifies the pole and continuum sectors. We also discuss a possible extension to string-inspired coupled-channel systems, and illustrate that higher-dimensional dS black holes can be treated within the same framework, at least in tensor- and vector-type sectors. Our results indicate that complex scaling offers a useful spectral framework for analyzing both quasinormal modes and continuum response in black-hole physics.
Related
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BibTeX
@misc{ogawa2026quasinormal,
title = {{Quasinormal modes and continuum response of de Sitter black holes via complex scaling method}},
author = {Shoya Ogawa and Okuto Morikawa and Takuya Hirose},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.03277},
eprint = {2605.03277},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.03277},
}
RIS
TY - UNPB
TI - Quasinormal modes and continuum response of de Sitter black holes via complex scaling method
AU - Shoya Ogawa
AU - Okuto Morikawa
AU - Takuya Hirose
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2605.03277
UR - https://arxiv.org/abs/2605.03277
AB - We apply the complex scaling method to black-hole perturbations in four-dimensional Schwarzschild--de~Sitter (dS) spacetimes. The method converts the outgoing-wave boundary-value problem into a non-Hermitian spectral problem and enables quasinormal-mode poles and the rotated continuum to be treated in a common framework. We focus in particular on the continuum level density, which characterizes the continuum response beyond isolated quasinormal-mode frequencies. Using Regge--Wheeler-type perturbation equations for scalar, electromagnetic, and gravitational fields, we investigate how a nonzero cosmological constant modifies the pole and continuum sectors. We also discuss a possible extension to string-inspired coupled-channel systems, and illustrate that higher-dimensional dS black holes can be treated within the same framework, at least in tensor- and vector-type sectors. Our results indicate that complex scaling offers a useful spectral framework for analyzing both quasinormal modes and continuum response in black-hole physics.
ER -