Strange Quark Stars in 4D Einstein–Gauss–Bonnet Gravity

Abstract

The existence of strange matter in compact stars may give rise to striking outcomes of the various physical phenomena. As an alternative to neutron stars, a new class of compact stars called strange stars should exist if the strange matter hypothesis is true. In this paper, we investigate the possible construction of strange stars in quark matter phases based on the MIT bag model. We consider scenarios in which strange stars have no crusts. Then we apply two types of equations of state to quantify the mass–radius diagram for static strange star models, performing the numerical calculation of the modified Tolman–Oppenheimer–Volkoff equations in the context of 4D Einstein–Gauss–Bonnet (EGB) gravity. It is worth noting that the GB term gives rise to a nontrivial contribution to the gravitational dynamics in the limit D → 4. However, the claim that the resulting theory is one of pure gravity has been cast in doubt on several grounds. Thus, we begin our discussion by showing the regularized 4D EGB theory has an equivalent action as the novel 4D EGB in a spherically symmetric spacetime. We also study the effects of coupling constant α on the physical properties of the constructed strange stars including the compactness and criterion of adiabatic stability. Finally, we compare our results to those obtained from standard general relativity.

Electrically charged quark stars in 4D Einstein–Gauss–Bonnet gravity

“…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. A comprehensive analysis about stellar structure models within this framework have been exhaustively studied, see for example [40][41][42][43]. Wormhole and thin-shell wormholes have been studied as well [44,45].…”

“…Thus, it reflects that regularized procedures are not unique. It is however worthwhile to remark that spherically-symmetric 4D solutions still remain valid in these regularized theories [41] as of original prescription presented in [14].…”

Charged stars in 4D Einstein–Gauss–Bonnet gravity

“…[75], the treatment was found to be consistent by breaking the fourdimensional diffeomorphism invariance (see also [76] in the cosmological context). However, it is interesting to note that the spherically symmetric 4D solutions still remain valid in these regularized theories [43]. In fact, the black hole solutions via rescaling procedure [7] still remains valid in these regularized theories [73,77].…”

“…Additionally, strange stars and their phenomenological properties have been extensively investigated with different EoS in [42] (see Ref. [43,44] for more). Moreover, in Ref.…”

Thin accretion disks around rotating black holes in 4D Einstein–Gauss–Bonnet gravity

“…For instance, charged and rotating 4D EGB BH solutions [42][43][44], BH solutions in Lovelock gravity [45,46], BH solutions surrounded by clouds of strings [47], Bardeen BHs [48], Hayward BHs [49], spherically symmetric and thin shell wormhole solutions [50,51] and relativistic stars [52] have been extensively studied. Also, a large number of interesting aspects of the theory including geodesic motion and shadow [53][54][55][56], strong and weak gravitational lensing [57][58][59][60], quasinormal modes of BHs [61][62][63][64][65], instability of (A)dS BHs [66][67][68], thermodynamics and phase transition [69][70][71][72], Hawking radiation [73,74] and new quark stars [75,76] have also been stud-ied. For further references on 4D EGB gravity see [77][78][79][80][81][82][83][84][85][86][87]…”