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Main Authors: Liu, Hang, Guo, Hong
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.23934
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author Liu, Hang
Guo, Hong
author_facet Liu, Hang
Guo, Hong
contents In this paper, we adopt continued fraction method (CFM) associated with VBK approach, which is recently developed by Vieira, Bezerra and Kokkotas, to investigate the spectrum of quasibound states (QBS) and superradiant instability of massive scalar perturbation imposed on analog rotating black hole in photon-fluid model. We analyze the effects of black hole angular velocity $Ω_H$ and scalar field mass $μ$ on QBS spectrum with positive and negative winding number $m=\pm1$, respectively. In addition to the fundamental frequency, we also investigate the overtones in order to disclose more distinctions of spectrum between the states of $m=\pm 1$. We show that the sign of winding number can produce notable impacts on the spectrum, particularly to the imaginary part of the spectrum. We study the superradiant instability and find that the maximum instability for a given $Ω_H$ is not in monotonic relationship with angular velocity, which is in contrast to the case in Kerr black hole spacetime. As expected, the strength of superradiant instability can be significantly weakened by increasing the winding number. These findings imply that there exists a critical angular velocity under which the instability is strongest in parameter space, and we are supposed to find it out at $m=1$. Indeed, this max instability is found to be $ω_{Imax}\approx 1.13374\times 10^{-5}$ related to the critical angular velocity $Ω_H\approx1.22$.
format Preprint
id arxiv_https___arxiv_org_abs_2509_23934
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quasibound States and Superradiant Instability of Black Hole in Analog Gravity
Liu, Hang
Guo, Hong
General Relativity and Quantum Cosmology
In this paper, we adopt continued fraction method (CFM) associated with VBK approach, which is recently developed by Vieira, Bezerra and Kokkotas, to investigate the spectrum of quasibound states (QBS) and superradiant instability of massive scalar perturbation imposed on analog rotating black hole in photon-fluid model. We analyze the effects of black hole angular velocity $Ω_H$ and scalar field mass $μ$ on QBS spectrum with positive and negative winding number $m=\pm1$, respectively. In addition to the fundamental frequency, we also investigate the overtones in order to disclose more distinctions of spectrum between the states of $m=\pm 1$. We show that the sign of winding number can produce notable impacts on the spectrum, particularly to the imaginary part of the spectrum. We study the superradiant instability and find that the maximum instability for a given $Ω_H$ is not in monotonic relationship with angular velocity, which is in contrast to the case in Kerr black hole spacetime. As expected, the strength of superradiant instability can be significantly weakened by increasing the winding number. These findings imply that there exists a critical angular velocity under which the instability is strongest in parameter space, and we are supposed to find it out at $m=1$. Indeed, this max instability is found to be $ω_{Imax}\approx 1.13374\times 10^{-5}$ related to the critical angular velocity $Ω_H\approx1.22$.
title Quasibound States and Superradiant Instability of Black Hole in Analog Gravity
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2509.23934