Scalar Quasi-Normal Modes in Black Hole Gravitational Lensing

Fuente: arXiv
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Main Authors: Yin, Chengjiang, Lin, Zihao, He, Jian-hua
Format: Preprint
Published: 2026
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author Yin, Chengjiang
Lin, Zihao
He, Jian-hua
author_facet Yin, Chengjiang
Lin, Zihao
He, Jian-hua
contents We investigate the excitation of quasi-normal modes (QNMs) in gravitational lensing by a Schwarzschild black hole using a scalar field model. By employing a time-domain mode-sum method, we analyze the complex interplay between an incident burst signal and the black hole spacetime. We find that the incident waves can non-resonantly excite a substantial number of high-$l$ modes, with amplitudes for modes as high as l=20 remaining significant compared to the fundamental l=0 mode. We confirm through QNM template fitting that the late-time behaviors of these excited modes are indeed QNMs. After passing through the black hole, we find that the lensed waves form a highly directional and coherent Gaussian beam whose cross-sectional intensity profile is well-described by a Gaussian profile. Unlike spherical waves, this beam's amplitude does not decrease with distance from the black hole but remains nearly constant in the near-field region. Moreover, due to the superposition of numerous QNMs, oscillations largely cancel each other out. The lensed temporal waves do not exhibit typical oscillatory patterns.
format Preprint
id arxiv_https___arxiv_org_abs_2601_14303
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Scalar Quasi-Normal Modes in Black Hole Gravitational Lensing
Yin, Chengjiang
Lin, Zihao
He, Jian-hua
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
We investigate the excitation of quasi-normal modes (QNMs) in gravitational lensing by a Schwarzschild black hole using a scalar field model. By employing a time-domain mode-sum method, we analyze the complex interplay between an incident burst signal and the black hole spacetime. We find that the incident waves can non-resonantly excite a substantial number of high-$l$ modes, with amplitudes for modes as high as l=20 remaining significant compared to the fundamental l=0 mode. We confirm through QNM template fitting that the late-time behaviors of these excited modes are indeed QNMs. After passing through the black hole, we find that the lensed waves form a highly directional and coherent Gaussian beam whose cross-sectional intensity profile is well-described by a Gaussian profile. Unlike spherical waves, this beam's amplitude does not decrease with distance from the black hole but remains nearly constant in the near-field region. Moreover, due to the superposition of numerous QNMs, oscillations largely cancel each other out. The lensed temporal waves do not exhibit typical oscillatory patterns.
title Scalar Quasi-Normal Modes in Black Hole Gravitational Lensing
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2601.14303