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Main Authors: Bian, Wen-Hao, Cui, Zhu-Fang
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.05988
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author Bian, Wen-Hao
Cui, Zhu-Fang
author_facet Bian, Wen-Hao
Cui, Zhu-Fang
contents We investigate the quasinormal modes (QNMs) associated with intrinsic metric-dilaton coupled perturbations of the Mandal-Sengupta-Wadia (MSW) black hole in two-dimensional string theory. Through suitable field redefinitions, the gravity-dilaton system is expressed in terms of the conformal factor and a redefined dilaton field, allowing the linear perturbation equations to be reduced to coupled Schrodinger-type eigenvalue equations in the tortoise coordinate. By imposing the standard QNMs' boundary conditions of purely ingoing waves at the horizon and purely outgoing waves at spatial infinity, we numerically determine the complex frequency spectrum. All modes satisfy Im$(ω)<0$, confirming the linear stability of the MSW black hole under intrinsic coupled perturbations. Unlike external scalar-field perturbations, which yield purely imaginary frequencies, the intrinsic perturbations generically exhibit nonvanishing real parts, corresponding to oscillatory modes of the gravity-dilaton sector. The real part of the frequency displays a nonmonotonic dependence on the overtone number, while increasing the central-charge parameter $\sqrt{k}$ systematically decreases the damping rate and prolongs the relaxation time. These results indicate that intrinsic perturbations probe internal dynamical degrees of freedom and reveal characteristic features of the relaxation dynamics of two-dimensional stringy black holes.
format Preprint
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institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quasinormal modes of coupled metric-dilaton perturbations in two-dimensional stringy black holes
Bian, Wen-Hao
Cui, Zhu-Fang
General Relativity and Quantum Cosmology
High Energy Physics - Theory
We investigate the quasinormal modes (QNMs) associated with intrinsic metric-dilaton coupled perturbations of the Mandal-Sengupta-Wadia (MSW) black hole in two-dimensional string theory. Through suitable field redefinitions, the gravity-dilaton system is expressed in terms of the conformal factor and a redefined dilaton field, allowing the linear perturbation equations to be reduced to coupled Schrodinger-type eigenvalue equations in the tortoise coordinate. By imposing the standard QNMs' boundary conditions of purely ingoing waves at the horizon and purely outgoing waves at spatial infinity, we numerically determine the complex frequency spectrum. All modes satisfy Im$(ω)<0$, confirming the linear stability of the MSW black hole under intrinsic coupled perturbations. Unlike external scalar-field perturbations, which yield purely imaginary frequencies, the intrinsic perturbations generically exhibit nonvanishing real parts, corresponding to oscillatory modes of the gravity-dilaton sector. The real part of the frequency displays a nonmonotonic dependence on the overtone number, while increasing the central-charge parameter $\sqrt{k}$ systematically decreases the damping rate and prolongs the relaxation time. These results indicate that intrinsic perturbations probe internal dynamical degrees of freedom and reveal characteristic features of the relaxation dynamics of two-dimensional stringy black holes.
title Quasinormal modes of coupled metric-dilaton perturbations in two-dimensional stringy black holes
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2604.05988