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

Toshmatov, Bobir; Stuchlík, Zdeněk; Ahmedov, Bobomurat

doi:10.1103/physrevd.98.085021

Cited by 45 publications

(19 citation statements)

References 46 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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“…Rotating, electric and magnetic regular BH solutions obtained by coupling general relativity to nonlinear electrodynamics obeying the singularity problem and physical properties of the BHs such as thermodynamics, thermal stability and possible phase transition, QNMs and photon motions are studied in, e.g., refs. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Regular BHs in modified gravity have been investigated in [24].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Test Particles and Twin Peaks QPOs around Regular Black Holes in Modified Gravity

et al. 2021

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In this work, we have presented a detailed analysis of the event horizon of regular black holes (BHs) in modified gravity known as MOG, the so-called regular MOG BH. The motion of neutral particles around the BH has also been explored. The test particle motion study shows that the positive (negative) values of the MOG parameter mimic the spin of a rotating Kerr BH, providing the same values for the innermost stable pro-grade (retrograde) orbits of the particles in the range of the spin parameter a/M∈(−0.4125,0.6946). The efficiency of energy release from the accretion disk by the Novikov–Thorne model has been calculated, and the efficiency was shown to be linearly proportional to the increase of the MOG parameter α. Moreover, we have developed a new methodology to test gravity theories in strong-field regimes using precision data from twin-peaked quasiperiodic oscillations (QPOs) of objects calculating possible values of upper and lower frequencies. However, it is obtained that the positive MOG parameter can not mimic the spin of Kerr BHs in terms of the same QPO frequencies. We have provided possible ranges for upper and lower frequencies of twin-peak QPOs with the ratio of the upper and lower frequencies of 3:2 around regular MOG BHs in the different models. Moreover, as an example, we provide detailed numerical analysis of the QPO of GRS 1915+105 with the frequencies νU=168±5Hz and νL=113±3Hz. It is shown that the central BH of the QPO object can be a regular MOG BH when the value of the parameter is α=0.2844−0.1317+0.0074 and shines in the orbits located at the distance r/M=7.6322−0.0826+0.0768 from the central BH. It is also shown that the orbits where QPOs shine are located near the innermost stable circular orbit (ISCO) of the test particle. The correlation between the radii of ISCO and the QPO orbits is found, and it can be used as a new theoretical way to determine ISCO radius through observational data from the QPOs around various compact objects.

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“…The thermodynamic properties of Bardeen's solution have been investigated in [6]. The properties of the regular black hole solutions with nonlinear electric and magnetic charges have been studied in [7][8][9][10][11][12][13][14][15][16][17][18]. In the framework of tensor-vector-scalar (TeVeS) gravity proposed by Moffat and called Modified Gravity (MOG), the regular black hole solutions have been also discussed [19].…”

Section: Introductionmentioning

confidence: 99%

Regular Bardeen Black Holes in Anti-de Sitter Spacetime versus Kerr Black Holes through Particle Dynamics

et al. 2021

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In this work, test particle dynamics around a static regular Bardeen black hole (BH) in Anti-de Sitter spacetime has been studied. It has been shown for neutral test particles that parameters of a regular Bardeen black hole in Anti-de Sitter spacetime can mimic the rotation parameter of the Kerr metric up to the value a≈0.9 providing the same innermost stable circular orbit (ISCO) radius. We have also explored the dynamics of magnetized particles with a magnetic dipole moment around a magnetically charged regular Bardeen black hole in Anti-de Sitter spacetime. As a realistic astrophysical scenario of the study, we have treated neutron stars orbiting a supermassive black hole (SMBH), in particular, the magnetar PSR J1745-2900 orbiting Sgr A* with the parameter β=10.2, as magnetized test particles. The magnetized particles dynamics shows that the parameter β, negative values of cosmological constant and magnetic charge parameter of the central BH cause a decrease in the ISCO radius. We have compared the effects of the magnetic charge of the Bardeen BH with the spin of rotating Kerr BH and shown that magnetic charge parameter can mimic the spin in the range a/M≃(0,0.7896) when Λ=0 at the range of its values g/M≃(0,0.648).

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

Abstract: 1 Coupling general relativity to the linear or Maxwell electrodynamic field gives the Reissner-Nordström (RN) black hole solution which is singular at the origin of the spacetime r = 0.

Cited by 45 publications

References 46 publications

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

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

Dynamics of Test Particles and Twin Peaks QPOs around Regular Black Holes in Modified Gravity

Regular Bardeen Black Holes in Anti-de Sitter Spacetime versus Kerr Black Holes through Particle Dynamics

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