Optical features of AdS black holes in the novel 4D Einstein-Gauss-Bonnet gravity coupled to nonlinear electrodynamics

Abstract

An alternative theory of gravity that has attracted much attention recently is the novel fourdimensional Einstein-Gauss-Bonnet (4D EGB) gravity. The theory is rescaled by the Gauss-Bonnet (GB) coupling constant α → α/(D − 4) in D dimensions and redefined as four-dimensional gravity in the limit D → 4. Thus, in this manner, the GB term yields a non-trivial contribution to the gravitational dynamics. In fact, regularized black hole solutions and applications in the novel 4D EGB gravity have also been extensively explored. In this work, motivated by recent astrophysical observations, we present an in-depth study of the optical features of AdS black holes in the novel 4D EGB gravity coupled to exponential nonlinear electrodynamics (NED), such as the shadow geometrical shape, the energy emission rate, the deflection angle and quasinormal modes. Taking into account these dynamic quantities, we investigate the effects on the black hole solution by varying the parameters of the models. More specifically, we show that the variation of the GB and NED parameters, and of the cosmological constant, imprints specific signatures on the optical features of AdS black holes in the novel 4D EGB gravity coupled to nonlinear electrodynamics, thus leading to the possibility of directly testing these black hole models by using astrophysical observations.

Einstein−Gauss−Bonnet gravity with nonlinear electrodynamics

“…We will use the semi-analytical WKB approximation [44], [67]. In the third order expansion the frequencies are [30] (…”

“…Some aspects of the 4D EGB gravity theory were considered in [8]- [20]. The BH solutions in the 4D EGB model coupled to nonlinear electrodynamics (NED) were also studied in [21]- [30].It was shown in [31] that for a static spherically symmetric ansatz, in a conformally flat metric, only the GB term gives the finiteness of renormalization. The metric obtained is the rigorous solution for quantum gravity corrections and at short distances the repulsive force occurs.…”

“…Some aspects of the 4D EGB gravity theory were considered in [8]- [20]. The BH solutions in the 4D EGB model coupled to nonlinear electrodynamics (NED) were also studied in [21]- [30].…”

“…The event horizon radii, photon sphere and shadow radii for a=2, c=1 + 1.05 1 30. 1.78 2.20 2.62 3.43 3.83 4.23 9.76 x p 2.12 2.37 2.97 3.57 4.16 5.35 5.94 6.53 14.78 x s 4.28 4.68 5.68 6.68 7.69 9.71 10.73 11.74 26.00…”

Electrically Charged Quark Stars in $4D$ Einstein-Gauss-Bonnet Gravity

“…Research on 4D EGB gravity broadened rapidly among the scientific community, such as black hole solutions [16][17][18][19][20][21][22][23], a Vaidya-like radiating black hole in Ref. [24], black holes coupled to magnetic charge and nonlinear electrodynamics [25,26] and charged black hole [27,28]. Furthermore, deflection of light by black holes [29][30][31], weak cosmic censorship conjecture [32], quasi-normal modes [33][34][35] and shadow cast by black holes [36][37][38][39] have been fully investigated.…”