Bardeen Black Holes in the Regularized 4D Einstein–Gauss–Bonnet Gravity

Kumar, Arun; Kumar, Rahul; Ghosh, Sushant G.

doi:10.3390/universe8040232

Cited by 29 publications

(12 citation statements)

References 96 publications

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“…Nevertheless, several researchers attracted to analyse this 4D EGB theory, in particular, the spherically symmetric black hole solution obtained by Glavan and Lin [17] was extended to include charge [20], a nonstatic Vaidya-like radiating black hole in Ref. [21,22], black holes coupled with NED [23][24][25], with cloud of string background [26]. The black hole stability and quasinormal modes are also widely discussed [27][28][29][30][31][32], and the rotating counter of the black holes obtained [33,34].…”

Section: Introductionmentioning

confidence: 99%

Nonsingular black hole chemistry in $4D$ Einstein-Gauss-Bonnet gravity

Kumar,

Ghosh

2023

Preprint

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The EGB is an outcome of quadratic curvature corrections to the Einstein-Hilbert gravity action in the form of a Gauss-Bonnet (GB) term in D > 4 dimensions, and EGB gravity is topologically invariant in 4D. Several ways have been proposed for regularizing the D → 4 limit of EGB for non-trivial gravitational dynamics in 4D. Motivated by the importance of AdS/CFT, we obtain an exact static spherically symmetric nonsingular black hole in 4D EGB gravity coupled to the nonlinear electrodynamics (NED) in an AdS spacetime. We interpret the negative cosmological constant Λ as the positive pressure, via P = −Λ/8π, of the system's thermodynamic properties of the nonsingular black hole with an AdS background. We find that for P < Pc, the black holes with CP > 0 are stable to thermal fluctuations and unstable otherwise. We also analyzed the Gibbs free energy to find that the small globally unstable black holes undergo a phase transition to the large globally stable black holes. Further, we study the P − V criticality of the system and then calculate the critical exponents to find that our system behaves like Van der Walls fluid.

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Section: Introductionmentioning

confidence: 99%

Nonsingular black hole chemistry in $4D$ Einstein-Gauss-Bonnet gravity

Kumar,

Ghosh

2023

Preprint

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“…Thus, the black hole interior does not result in a singularity but develops a de Sitter-like region, eventually settling with a regular center; thus, its maximal extension is one of a Reissner-Nordström spacetime but with a regular center (Borde 1994(Borde , 1997. Also a significant amount of attention has been devoted to finding an extension, and the uncovering of the properties of Bardeen black holes has been reported (Ansoldi 2008;Lemos & Zanchin 2011;Sharif & Javed 2011;Fernando & Correa 2012;Flachi & Lemos 2013;Bambi 2014;Ulhoa 2014;Ghosh & Amir 2015;Schee & Stuchlik 2015;Breton & Lopez 2016;Saleh et al 2018;Ali & Ghosh 2019;Dey & Chakrabarti 2019;Toshmatov et al 2019;Kumar et al 2020aKumar et al , 2020bKumar et al 2022a;Islam et al 2022), and also in higher dimensional spacetimes (Ali & Ghosh 2018;Kumar et al 2019;Singh et al 2020). Interestingly, the Bardeen model may also be interpreted as a solution to Einstein equations with an electric source (Rodrigues & Silva 2018).…”

Section: Introductionmentioning

confidence: 99%

Testing Strong Gravitational Lensing Effects of Supermassive Compact Objects with Regular Spacetimes

Kumar

Islam

Ghosh

2022

ApJ

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We compare and contrast gravitational lensing, in the strong field limit, by the photon sphere in spherically symmetric regular electrically charged (REC) black holes (0 < b ≤ b E ) and with those by corresponding REC no-horizon spacetimes (b > b E ). Here, b is an additional parameter due to the charge and the value b = b E ≈ 0.226 corresponds to an extremal black hole with degenerate horizons. Interestingly, the spacetime admits a photon sphere for 0 < b ≤ b P ≈ 0.247 and an anti-photon sphere only for b E < b ≤ b P . With no-horizon spacetime, images by lensing from the inside of the photon sphere (u < u ps) can also appear. Interestingly, for the case of u < u ps the deflection angle α D increases with u. We analyze the lensing observables by modeling compact objects Sgr A*, M87*, NGC 4649, and NGC 1332 as black holes and no-horizon spacetimes. The angular position θ ∞ and photon sphere radius x ps decrease with increasing parameter b. Our findings suggest that the angular separations (s) and magnification (r) of relativistic images inside the photon sphere may be higher than those outside. Moreover, the time delay for Sgr A* and M87* can reach ∼8.8809 and ∼12,701.8 minutes, respectively, at b = 0.2, deviating from Schwarzschild black holes by ∼2.615 and ∼4677 minutes. These deviations are insignificant for Sgr A* because it is too small, but they are sufficient for astronomical observation of M87* and some other black holes. With EHT bounds on the θ sh of Sgr A* and M87* within the 1σ region, placing bounds on the parameter b, our analysis concludes that REC black holes agree with the EHT results in finite space, whereas the corresponding REC no-horizon spacetimes are completely ruled out.

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“…Shamir and Mustafa [6] have developed the new family of charged anisotropic compact star using Bardeen's analysis as an exterior space time. Kumar et al [7] have analyzed the exact thermodynamics quantities of Bardeen black hole. Gedala et al [8] discovered two new exact and analytic solution of Einstein Maxwell field equation in the context of Bardeen black hole also satisfying embedding conditions.…”

Section: Introductionmentioning

confidence: 99%

Bardeen compact stars in modified f(R) gravity with conformal motion

Shamir

Rashid

2022

Int. J. Geom. Methods Mod. Phys.

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The main emphasis of this paper is to find the viable solutions of Einstein Maxwell field equations of compact star in context of modified [Formula: see text] theory of gravity. Two different models of modified [Formula: see text] gravity are considered. In particular, we choose isotropic matter distribution and Bardeen’s model for compact star to find the boundary conditions as an exterior space-time geometry. We use the conformal Killing geometry to compute the metric potentials. We discuss the behavior of energy density and pressure distribution for both models. Moreover, we analyze different physical properties such as behavior of energy density and pressure, equilibrium conditions, equation of state parameters, causality conditions and adiabatic index. It is noticed that both [Formula: see text] gravity models are suitable and provide viable results with Bardeen geometry.

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Bardeen Black Holes in the Regularized 4D Einstein–Gauss–Bonnet Gravity

Cited by 29 publications

References 96 publications

Nonsingular black hole chemistry in $4D$ Einstein-Gauss-Bonnet gravity

Nonsingular black hole chemistry in $4D$ Einstein-Gauss-Bonnet gravity

Testing Strong Gravitational Lensing Effects of Supermassive Compact Objects with Regular Spacetimes

Bardeen compact stars in modified f(R) gravity with conformal motion

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