Quasibound states, stability and wave functions of the test fields in 4D Einstein--Gauss--Bonnet gravity

Vieira, H. S.

doi:10.48550/arxiv.2107.02065

Cited by 6 publications

(8 citation statements)

References 16 publications

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“…The fact that incident waves can be superradiantly amplified when scattered off of charged BHs is closely connected with the properties of the underlying effective potential. In RNdS spacetime, spherically-symmetric ( = 0) charge scalar perturbations form quasibound states [29,[80][81][82][83] localized at a potential well which is present right outside the photon sphere (see Fig. 1).…”

Section: Quasinormal Modesmentioning

confidence: 99%

Charged black holes in de Sitter space: Superradiant amplification of charged scalar waves and resonant hyperradiation

2022

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Black holes typically inhabit highly dynamical galactic environments and are frequently permeated by accretion media. The inevitable scattering of scalar, electromagnetic and gravitational waves off rotating and charged black holes provides a remarkable demonstration of the energy extraction and subsequent amplification of scattered waves under the expense of the compact object's rotational and electromagnetic energy; a phenomenon known as superradiance. Certain circumstances tremendously favor the energy extraction process in such extent that linear superradiant instabilities are triggered. We examine the superradiant amplification of monochromatic charged scalar fields impinging Reissner-Nordström-de Sitter black holes which are known to exhibit superradiantly unstable quasinormal modes. We find that even though the frequency range of superradiance is reduced when a positive cosmological constant is incorporated, the amplification factors are significantly elevated with respect to those occurring in Reissner-Nordström spacetime. Intriguingly, we confirm that the long-lived quasinormal resonances that reside in the superradiant regime induce resonant peaks when the wave's frequency matches the real part of the quasinormal mode, regardless of the spacetime's modal stability.

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Section: Quasinormal Modesmentioning

confidence: 99%

Charged black holes in de Sitter space: Superradiant amplification of charged scalar waves and resonant hyperradiation

2022

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“…In addition, we can compute the transition frequency, ∆ω, between two highly damped (n → ∞) neighboring states [20]. It is given by…”

Section: Quasistationary Levels and Wave Functionsmentioning

confidence: 99%

Some aspects of the five-dimensional Lovelock black hole spacetime: strong homotopy retract, perihelion precession and quasistationary levels

Abu-Saleem,

Vieira

2021

Preprint

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In this work we explore some mathematical physics aspects of the spherically symmetric Lovelock black hole in high dimensions. Intended for this aim, we thoroughly consider the metric corresponding to the five-dimensional Lovelock black hole spacetime. We construct the strong retractions by the geodesic equations on the background under consideration. As a result, from the topological point of view, we construct the theory of strong homotopy retract, which will allow us, in principle, to better understand some of its suitable applications on astrophysics and cosmology, in particular, in the analysis of the spacetime singularities. We find the solutions of the equation of motion for both radial and angular coordinates, and then we describe the outer ("exterior") and lower ("interior") apparent horizons. Indeed, the outer apparent horizon is the last surface from which the light waves could still escape from the black hole. Thus, it is meaningful to analyze some physical phenomena related to quantum particles propagating outside the exterior apparent horizon, in particular, we discuss the quasistationary levels of scalar fields and their radial wave functions, which are given in terms of the general Heun functions. We also calculate the perihelion precession in this background.

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“…The quasinormal modes of the 4D-EGB black hole in the asymptotically de Sitter and anti-de Sitter spacetime due to scalar, electromagnetic and Dirac perturbations has been studied in [39,40]. The quasibound states of massless scalar, electromagnetic and Dirac fields in the asymptotically flat 4D-EGB black hole and the associated stability problem has been studied recently in [58].…”

Section: Introductionmentioning

confidence: 99%

“…This naturally begs for the answer to the question that whether such a spacetime with a central naked singularity is at all stable under perturbation? If so, how its response will be different from that of a standard 4D-EGB black hole [30,57,58]?…”

Section: Introductionmentioning

confidence: 99%

Naked singularity in 4D Einstein-Gauss-Bonnet novel gravity: Echoes and (in)-stability

Chowdhury,

Devi,

Chakrabarti

2022

Preprint

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We study the stability of an asymptotically flat, static, spherically symmetric naked singularity spacetime in the novel four dimensional Einstein-Gauss-Bonnet (EGB) gravity. The four dimensional EGB black hole for large enough values of the coupling parameter leads to such a naked singularity. The stability and the response of the spacetime is studied against the perturbations by test scalar, electromagnetic and Dirac fields and the time evolution of these perturbations were observed numerically. Implementing a null Dirichlet boundary condition near the singularity, we observed that for l = 1 modes of scalar, electromagnetic perturbation and l = 0, 1 modes of Dirac perturbation the time-domain profile give rise to distinct echoes. However, as the coupling constant is increased, the echoes align and the QNM structure of the 4D-EGB naked singularity-spacetime becomes prominent. For higher values of the multipole number, the spacetime becomes unstable, thereby restricting the parameter space for the coupling parameter.

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Quasibound states, stability and wave functions of the test fields in 4D Einstein--Gauss--Bonnet gravity

Cited by 6 publications

References 16 publications

Charged black holes in de Sitter space: Superradiant amplification of charged scalar waves and resonant hyperradiation

Charged black holes in de Sitter space: Superradiant amplification of charged scalar waves and resonant hyperradiation

Some aspects of the five-dimensional Lovelock black hole spacetime: strong homotopy retract, perihelion precession and quasistationary levels

Naked singularity in 4D Einstein-Gauss-Bonnet novel gravity: Echoes and (in)-stability

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