From driven oscillations to free ringdown: a particle plunging into Kerr
Abstract
We show that a ringdown waveform can admit a constant-coefficient quasinormal-mode (QNM) representation while its individual QNM-pole contributions remain driven. To establish this result, we construct a first-principles rational approximation to the Kerr Green's function from its QNM poles, physical residues, and horizon-frequency zeros. For particles plunging from the innermost stable circular orbit into Kerr black holes with spins 0.5-0.9, each QNM-pole contribution initially follows the source's instantaneous complex frequency and decouples only after the source decays faster than the corresponding mode. At late times, the source approaches a sum of damped oscillations at the third and higher horizon frequencies. The corresponding zeros in the Green's function cancel these source-frequency components in the coherent waveform, while the continuing drive generates oscillations at QNM frequencies. Thus, an apparently free QNM superposition can emerge before its individual contributions dynamically decouple from the source.
Related
- Dynamics, ringdown, and accretion-driven multiple quasi-periodic oscillations of Kerr–Bertotti–Robinson black holes
- Probing Nonlinear Logarithmic Kalb-Ramond Black Holes: Particle Dynamics, Epicyclic Oscillations and Thermodynamic Signatures
- Model-independent and reconstruction-free evidence for cosmic acceleration from DESI baryon acoustic oscillations
- Analysis of wave processes using beam-driven Langmuir/Z-mode waveforms generated in particle-in-cell simulations
- The influence of free-free absorption on the radio spectrum of Particle-Accelerating Colliding-Wind Binaries
BibTeX
@misc{weller2026from,
title = {{From driven oscillations to free ringdown: a particle plunging into Kerr}},
author = {Colin Weller and Andrew Laeuger and Fulin Li and Neil Lu and Rowina S. Nathan and Sizheng Ma and Yanbei Chen and Ling Sun},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09531},
eprint = {2609.09531},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.09531},
}
RIS
TY - UNPB
TI - From driven oscillations to free ringdown: a particle plunging into Kerr
AU - Colin Weller
AU - Andrew Laeuger
AU - Fulin Li
AU - Neil Lu
AU - Rowina S. Nathan
AU - Sizheng Ma
AU - Yanbei Chen
AU - Ling Sun
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.09531
UR - https://arxiv.org/abs/2609.09531
AB - We show that a ringdown waveform can admit a constant-coefficient quasinormal-mode (QNM) representation while its individual QNM-pole contributions remain driven. To establish this result, we construct a first-principles rational approximation to the Kerr Green's function from its QNM poles, physical residues, and horizon-frequency zeros. For particles plunging from the innermost stable circular orbit into Kerr black holes with spins 0.5-0.9, each QNM-pole contribution initially follows the source's instantaneous complex frequency and decouples only after the source decays faster than the corresponding mode. At late times, the source approaches a sum of damped oscillations at the third and higher horizon frequencies. The corresponding zeros in the Green's function cancel these source-frequency components in the coherent waveform, while the continuing drive generates oscillations at QNM frequencies. Thus, an apparently free QNM superposition can emerge before its individual contributions dynamically decouple from the source.
ER -