Dynamical thin shells in black hole ringdown
Abstract
We study how a radially oscillating thin shell outside a black hole (BH) affects gravitational wave ringdown and derive matching conditions for polar and axial perturbations from the linearized Israel junction conditions on the moving worldtube. Periodic shell motion produces Floquet sidebands in the scattered wave. For a distant shell, the motion has little effect on the prompt ringdown and only weakly modifies the late time echoes. When the shell is closer to the BH, a replica of a long lived shell mode enters the incident frequency band, increasing the late time echo amplitude by roughly two orders of magnitude. We also identify an exceptional point where two polar modes coalesce and find the contribution of its second order pole in the late time waveform.
Related
- Collective Onset of Matter-Induced Scalarization around a Black Hole with Two Thin Shells
- Dyonic black holes supporting nearly-black self-gravitating thin shells
- Quantum black hole ringdown
- Cubic Quasinormal Modes in the Black-Hole Ringdown
- How much of the black hole ringdown is sourced within the light ring?
BibTeX
@misc{hu2026dynamical,
title = {{Dynamical thin shells in black hole ringdown}},
author = {Han-Wen Hu and Chen Lan and Zong-Kuan Guo},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.03798},
eprint = {2610.03798},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.03798},
}
RIS
TY - UNPB
TI - Dynamical thin shells in black hole ringdown
AU - Han-Wen Hu
AU - Chen Lan
AU - Zong-Kuan Guo
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.03798
UR - https://arxiv.org/abs/2610.03798
AB - We study how a radially oscillating thin shell outside a black hole (BH) affects gravitational wave ringdown and derive matching conditions for polar and axial perturbations from the linearized Israel junction conditions on the moving worldtube. Periodic shell motion produces Floquet sidebands in the scattered wave. For a distant shell, the motion has little effect on the prompt ringdown and only weakly modifies the late time echoes. When the shell is closer to the BH, a replica of a long lived shell mode enters the incident frequency band, increasing the late time echo amplitude by roughly two orders of magnitude. We also identify an exceptional point where two polar modes coalesce and find the contribution of its second order pole in the late time waveform.
ER -