Gravitational-wave Echoes Beyond the Hubble Time from Quantum Black Holes
Abstract
We investigate gravitational-wave echoes in a horizonless compact object model, a non-perturbative solution of the semi-classical Einstein equation that reproduces the entropy-area law from the bulk structure. By employing a model of anisotropic fluids in classical general relativity (GR), we show that odd-parity gravitational waves are not reflected at the object's surface but are trapped inside due to the exponentially strong redshift, and that the echo-delay time extremely exceeds the age of the Universe. Consequently, the echo signals are effectively unobservable, which is consistent with current null results from echo searches. We finally discuss how this quantum black hole and the conventional classical black hole could be distinguished observationally.
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BibTeX
@misc{chen2026gravitationalwave,
title = {{Gravitational-wave Echoes Beyond the Hubble Time from Quantum Black Holes}},
author = {Che-Yu Chen and Naritaka Oshita and Yuki Yokokura},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.05886},
eprint = {2610.05886},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.05886},
}
RIS
TY - UNPB
TI - Gravitational-wave Echoes Beyond the Hubble Time from Quantum Black Holes
AU - Che-Yu Chen
AU - Naritaka Oshita
AU - Yuki Yokokura
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2610.05886
UR - https://arxiv.org/abs/2610.05886
AB - We investigate gravitational-wave echoes in a horizonless compact object model, a non-perturbative solution of the semi-classical Einstein equation that reproduces the entropy-area law from the bulk structure. By employing a model of anisotropic fluids in classical general relativity (GR), we show that odd-parity gravitational waves are not reflected at the object's surface but are trapped inside due to the exponentially strong redshift, and that the echo-delay time extremely exceeds the age of the Universe. Consequently, the echo signals are effectively unobservable, which is consistent with current null results from echo searches. We finally discuss how this quantum black hole and the conventional classical black hole could be distinguished observationally.
ER -