Resonance in black hole ringdown: Benchmarking quasinormal mode excitation and extraction

Fuente: arXiv
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Main Authors: Kubota, Kei-ichiro, Motohashi, Hayato
Format: Preprint
Published: 2025
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author Kubota, Kei-ichiro
Motohashi, Hayato
author_facet Kubota, Kei-ichiro
Motohashi, Hayato
contents We investigate how resonant excitation near exceptional points manifests in Kerr black hole ringdown waveforms and examine its extraction. Using waveforms generated by localized initial data, where quasinormal mode amplitudes are given solely by excitation factors, we establish a controlled benchmark for overtone extraction. Applying an iterative fitting method with mirror modes, we analyze a mild resonance in the $(l,m)=(2,2)$ multipole and a sharp resonance in the $(3,1)$ multipole occurring as part of a sequence of successive resonances. For $(2,2)$, we extract the fundamental mode, the first three overtones, and the fundamental mirror mode with relative errors below $10\%$, and show that residual waveforms exhibit the expected damped sinusoids together with distinctive resonance signatures. For $(3,1)$, we demonstrate that resonances can not only amplify but also reduce quasinormal mode excitations, reshaping the overtone hierarchy and rendering the sharp resonance more pronounced in ringdown. Our results clarify the imprint of resonance in Kerr ringdown and highlight both the robustness and limitations of current extraction techniques, providing a foundation for more reliable extraction of higher overtones and for applications to observational data analysis.
format Preprint
id arxiv_https___arxiv_org_abs_2509_06411
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Resonance in black hole ringdown: Benchmarking quasinormal mode excitation and extraction
Kubota, Kei-ichiro
Motohashi, Hayato
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
We investigate how resonant excitation near exceptional points manifests in Kerr black hole ringdown waveforms and examine its extraction. Using waveforms generated by localized initial data, where quasinormal mode amplitudes are given solely by excitation factors, we establish a controlled benchmark for overtone extraction. Applying an iterative fitting method with mirror modes, we analyze a mild resonance in the $(l,m)=(2,2)$ multipole and a sharp resonance in the $(3,1)$ multipole occurring as part of a sequence of successive resonances. For $(2,2)$, we extract the fundamental mode, the first three overtones, and the fundamental mirror mode with relative errors below $10\%$, and show that residual waveforms exhibit the expected damped sinusoids together with distinctive resonance signatures. For $(3,1)$, we demonstrate that resonances can not only amplify but also reduce quasinormal mode excitations, reshaping the overtone hierarchy and rendering the sharp resonance more pronounced in ringdown. Our results clarify the imprint of resonance in Kerr ringdown and highlight both the robustness and limitations of current extraction techniques, providing a foundation for more reliable extraction of higher overtones and for applications to observational data analysis.
title Resonance in black hole ringdown: Benchmarking quasinormal mode excitation and extraction
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
url https://arxiv.org/abs/2509.06411