Scalar perturbations of nonsingular nonrotating black holes in conformal gravity

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

doi:10.1103/physrevd.96.064028

Cited by 48 publications

(50 citation statements)

References 51 publications

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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: 49%

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: 49%

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

Rodrigues

Silva

2019

Phys. Rev. D

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“…3. On the other hand, the imaginary part of the QNM frequency in large N limit is independent of N , while it is linear in the overtone n (similar tendencies also appear for the QNMs of the massless scalar field perturbations [24]). One can see from the lower panel of Fig.…”

Section: Large N Limitmentioning

confidence: 61%

“…The QNMs generated by a massless scalar field and those by electromagnetic perturbations have been studied in Ref. [24]. In that paper, the authors neglected the back reaction of the fields on the spacetime.…”

Section: Axial Perturbationsmentioning

confidence: 99%

Gravitational perturbations of nonsingular black holes in conformal gravity

Chen

2019

Phys. Rev. D

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It is believed that in the near future, gravitational wave detections will become a promising tool not only to test gravity theories, but also to probe extremely curved spacetime regions in our universe, such as the surroundings of black holes. In this paper, we investigate the quasinormal modes (QNMs) of the axial gravitational perturbations of a class of non-singular black holes conformally related to the Schwarzschild black hole. These non-singular black holes can be regarded as the vacuum solution of a family of conformal gravity theories which are invariant under conformal transformations. After conformal symmetry is broken, these black holes produce observational signatures different from those of the Schwarzschild black hole, such as their QNM frequencies. We assume that the spacetime is described by the Einstein equation with the effective energy momentum tensor of an anisotropic fluid. The master equation describing the QNMs is derived, and the QNM frequencies are evaluated with the Wentzel-Kramers-Brillouin (WKB) method up to the 6th order. As expected, the QNM spectra of these non-singular black holes deviate from those of the Schwarzschild black hole, indicating the possibility of testing these black hole solutions with the help of future gravitational wave detections.

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“…In the former case, observational tests may be out of reach. In the latter case, we have the constraint L/M < 1.2 from the X-ray spectrum of astrophysical black holes [20,21], and independent constraints may be obtained from future observations of gravitational waves [22]. Moreover, the Schwarzschild metric rescaled by (5) is certanly a regular black hole's solution of the Weyl conformal gravity too.…”

Section: Introductionmentioning

confidence: 99%

Formation and evaporation of an electrically charged black hole in conformal gravity

et al. 2018

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Extending previous work on the formation and the evaporation of black holes in conformal gravity, in the present paper we study the gravitational collapse of a spherically symmetric and electrically charged thin shell of radiation. The process creates a singularity-free black hole. Assuming that in the evaporation process the charge Q is constant, the final product of the evaporation is an extremal remnant with M = Q, which is reached in an infinite amount of time. We also discuss the issue of singularity and thermodynamics of black holes in Weyl's conformal gravity.

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Scalar perturbations of nonsingular nonrotating black holes in conformal gravity

Cited by 48 publications

References 51 publications

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

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

Gravitational perturbations of nonsingular black holes in conformal gravity

Formation and evaporation of an electrically charged black hole in conformal gravity

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