Electromagnetic perturbations of black holes in general relativity coupled to nonlinear electrodynamics

Toshmatov, Bobir; Stuchlík, Zdeněk; Schee, Jan; Ahmedov, Bobomurat

doi:10.1103/physrevd.97.084058

Cited by 95 publications

(78 citation statements)

References 55 publications

(118 reference statements)

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“…We see that ρ, in (44) of [91] and X in (45) of [91], differ from what we obtained here, (37) and (38), so that is expected that the Lagrangian L BCX is different from (46) in [91]. The nonlinearity of the electromagnetic theory that generates this metric is described in Fig.…”

Section: Regular Black Hole With Three Horizonscontrasting

confidence: 50%

Regular multihorizon black holes in f(G) gravity with nonlinear electrodynamics

Rodrigues

Silva

2019

Phys. Rev. D

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In this work, we study the existence of regular black holes solutions with multihorizons in general relativity and in some alternative theories of gravity. We consider the coupling between the gravitational theory and nonlinear electrodynamics. The coupling generates modifications in the electromagnetic sector. This paper has as main objective generalize solutions already known from general relativity to the f (G) theory. To do that, we first correct some misprints of the Odintsov and Nojiri's work in order to introduce the formalism that will be used in the f (G) gravity. In order to satisfy all field equations, the method to find solutions in alternative theories generates different f (R) and f (G) functions for each solution, where only the nonlinear term of f (G) contributes to the field equations. We also analyze the energy conditions, since it is expected that some must be violated to find regular black holes, and using an auxiliary field, we analyze the nonlinearity of the electromagnetic theory. PACS numbers: 04.50.Kd, 04.70.Bw I. INTRODUCTIONBlack holes are one of the most interesting predictions of general relativity [1]. These objects have a region of non-scape where the boundary is a surface which permits the passage only in one direction, the event horizon [2]. The most simple black hole solution is described by the Schwarzschild metric, which is characterized only by its mass [3]. The structure of the Schwarzschild black hole is composed by an event horizon and a singularity in the black hole center [4]. There are several metrics that are more general than the Schwarzschild solution, such as the Reissner-Nordström (electrically charged), Kerr (with rotation) or de Sitter-like solutions (cosmological constant) [5]. The presence of these other parameters can lead to changes in the structure of black holes such as the Cauchy and cosmological horizon [3,5].Although some solutions have a singularity, this characteristic is not necessary for black holes. Actually, it is possible to find solutions that have an event horizon without singularity; this kind of solution is known as regular black hole [6]. James Bardeen proposed a metric which was later interpreted as a solution to the Einstein equations for nonlinear electrodynamics [7], without the presence of singularities [8]. As in the Reissner-Nordström case, due to the charge, Bardeen solution presents a Cauchy horizon [9]. Many solutions of regular black holes have arisen since then , and several studies of their properties have been conduct, such as absorption [32][33][34], scattering [35,36], quasinormal modes [37-50], thermodynamics [51-61] and even tidal forces [62].Beyond general relativity, we have the alternatives theories of gravity [63]. The Einstein equations could be obtained from the variational principle if we consider the Einstein-Hilbert action [64]. Modify this action is a way to find the field equations of these alternative theories [65]. One of the most studied modifications the f (R) theory [63], with R being the curvature scalar, whi...

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Section: Regular Black Hole With Three Horizonscontrasting

confidence: 50%

Regular multihorizon black holes in f(G) gravity with nonlinear electrodynamics

Rodrigues

Silva

2019

Phys. Rev. D

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“…In fact, this correspondence has been found violated in the Einstein-Lovelock theory with a spacetime dimension D > 4 [64,65]. Similar violation has also been found for the charged black holes in GR coupled with non-linear electrodynamics [66,67], and for the charged black holes in the Eddington-inspired-Born-Infeld gravity [46]. In the latter case, the non-trivial matter-geometry couplings inherent in the theory [68][69][70] may play a crucial role in causing this violation.…”

Section: Introductionmentioning

confidence: 63%

“…For example, for the higher dimensional black holes in the Lovelock gravity, this correspondence is not fulfilled in general [64,65]. Similar violation can be found even in GR when considering nonlinear electrodynamics [66,67]. Recently, a similar violation has been pointed out for the charged black holes in the Eddington-inspired-Born-Infeld gravity [46] and it may be due to the nontrivial matter-geometry coupling inherent in the theory.…”

Section: Eikonal Qnms and Photon Ringmentioning

confidence: 95%

Eikonal black hole ringings in generalized energy-momentum squared gravity

Chen

2020

Phys. Rev. D

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In the scope of black hole spectroscopy, several attempts have been made in the past decades in order to test black holes or gravitational theories via black hole quasinormal modes. In the eikonal approximation, the quasinormal modes are generically associated with the photon ring of the black hole. This correspondence is valid for most cases in general relativity, but may not be true in other theories of gravity. In this paper, we consider the generalized energy-momentum squared gravity in which matter fields are non-minimally coupled to geometry. We investigate the axial perturbations of the charged black holes in this model, without assuming any explicit expression of the action functional. After obtaining the modified Klein-Gordon equation and the modified Maxwell equations, we perturb the gravitational equations and the modified Maxwell equations to derive the coupled master equations of the axial perturbations. In the presence of the non-minimal coupling between matter and geometry, the correspondence between the eikonal quasinormal modes and the photon ring is not satisfied in general. Also, the two coupled fields of the axial perturbations are found to propagate independently and they do not share the same quasinormal frequencies in the eikonal limit.

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“…We have found a similar effect of the NED regime in the mapping of the images of the Keplerian disks due to the gravitational lensing and the frequency shift [59]; the results of the present paper are thus simply the other signature of this crucial effect of the NED regime. There is another important result related to the circular orbits of photons in the NED regime -it has been shown recently that the circular orbits of the effective geometry are closely related to the behaviour of both axial [82] and poloidal [83] electromagnetic perturbations of the NED regular black holes treated in the WKB approximation, while the scalar or gravitational perturbations are governed purely by the spacetime geometry, giving thus a modified version of the phenomenon envisaged in [? ].…”

Section: Discussionmentioning

confidence: 99%

Profiled spectral lines of Keplerian rings orbiting in the regular Bardeen black hole spacetimes

Schee

Stuchlík

2019

Eur. Phys. J. C

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Considering the regular Bardeen black hole spacetimes, we test the observational effects of the general relativistic solutions coupled to non-linear electrodynamics (NED) by studying the photon motion in the effective geometry governed by the spacetime geometry and the NED Lagrangian. We focus our attention to the observationally important case of profiled spectral lines generated by rings radiating in a fixed frequency and orbiting the black hole along circular geodesics of the Bardeen spacetime. Such profiled spectral lines are observed in active galactic nuclei and in microquasars, giving sufficient data for the test of regular black holes. We expect that such radiating rings could arise around the Galaxy central supermassive black hole SgrA*, and the related profiled spectral lines could give important additional information to those obtained by direct observations due to the Event Horizon (GRAVITY) Telescope. We demonstrate that the profiled spectral lines of the radiating rings predict strong signatures of the NED effects on the photon motionnamely the frequency shift to the red edge of the spectrum, and narrowing of the profile, by more than one order in comparison with the case of the profiles generated purely by the spacetime geometry, for all values of the magnetic charge and the inclination angle of the observer. The specific flux is substantially suppressed and for extended Keplerian disks even the shape of the profiled line is significantly modified due to the NED effect.

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Electromagnetic perturbations of black holes in general relativity coupled to nonlinear electrodynamics

Cited by 95 publications

References 55 publications

Regular multihorizon black holes in f(G) gravity with nonlinear electrodynamics

Regular multihorizon black holes in f(G) gravity with nonlinear electrodynamics

Eikonal black hole ringings in generalized energy-momentum squared gravity

Profiled spectral lines of Keplerian rings orbiting in the regular Bardeen black hole spacetimes

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