Influence of modification of gravity on spherical wormhole models

Yousaf, Z.; Ilyas, M.; Bhatti, M. Z.

doi:10.1142/s0217732317501632

Cited by 61 publications

(28 citation statements)

References 53 publications

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“…A careful study leads to the conclusion that, for the case of the wormhole solution given by ρ 1 and P 1 l of Eqs. (45) and (46), all energy conditions will be locally violated, and that this violation occurs far from the throat of the wormhole. Again, as in the case of the previous model, this violation comes from the α parameter of the R 2 term.…”

Section: Wormhole Models With R + αR 2 + 2f (T ) Gravitymentioning

confidence: 99%

Wormhole models in f(R,T) gravity

Elizalde

Khurshudyan

2019

Int. J. Mod. Phys. D

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Models of static wormholes within the f (R, T) extended theory of gravity are investigated and, in particular, the family f (R, T) = R + λT , with T = ρ + Pr + 2P l being the trace of the energymomentum tensor. Models corresponding to different relations for the pressure components (radial and lateral), and several equations of state (EoS), reflecting different matter content, are worked out explicitly. The solutions obtained for the shape functions of the generated wormholes obey the necessary metric conditions, as manifested in other studies in the literature. The respective energy conditions reveal the physical nature of the wormhole models thus constructed. It is found, in particular, that for each of those considered, the parameter space can be divided into different regions, in which the exact wormhole solutions fulfill the null (NEC) and the weak energy conditions (WEC), respectively, in terms of the lateral pressure. Moreover, the dominant energy condition (DEC) in terms of both pressures is also valid, while ρ + Pr + 2P l = 0. A similar solution for the theory Pr = ω1ρ + ω2ρ 2 is found numerically, where ω1 and ω2 are either constant or functions of r, leading to the result that the NEC in terms of the radial pressure is also valid. For non-constant ωi models, attention is focused on the behavior ωi ∝ r m . To finish, the question is addressed, how f (R) = R + αR 2 will affect the wormhole solutions corresponding to fluids of the form Pr = ω1ρ + ω2ρ 2 , in the three cases mentioned above. Issues concerning the nonconservation of the matter energy-momentum tensor, the stability of the solutions obtained, and the observational possibilities for testing these models are discussed in the last section.

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Section: Wormhole Models With R + αR 2 + 2f (T ) Gravitymentioning

confidence: 99%

Wormhole models in f(R,T) gravity

Elizalde

Khurshudyan

2019

Int. J. Mod. Phys. D

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“…Ref. [6] considers wormhole geometries filled with two physically different fluid configurations, one isotropic and another anisotropic, also leading to wormhole solutions without exotic matter. By contrast, in the present study, the avoidance of exotic matter can be attributed to two geometric rather than physical factors, the combined effects of f (R) gravity and noncommutative geometry.…”

Section: Introductionmentioning

confidence: 99%

Wormholes in f(R) gravity with a noncommutative-geometry background

Kuhfittig

2018

Indian J Phys

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This paper discusses the possible existence of traversable wormholes in f (R) modified gravity while assuming a noncommutative-geometry background, as well as zero tidal forces. The first part of the paper aims for an overview via several shape functions by determining the corresponding wormhole solutions and their properties. The solutions are made complete by deriving the modified-gravity functions F (r) and f (R), where F = df /dR. It is subsequently shown that the violation of the null energy condition can be attributed to the combined effects of f (R) gravity and noncommutative geometry. The second part of the paper reverses the strategy by starting with a special form of f (R) and determining the wormhole solution and the concomitant F (r). The approach in this paper differs in significant ways from that of Jamil et al., J. Korean Physical Soc. 65 917 (2014).

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“…Some observational tests [46,47] have been applied to f (R, T ) gravity in order to resolve the issues entailed by f (R) gravity. To understand f (R, T ) theory in detail, one may refer to some excellent work [48][49][50][51][52][53][54][55][56][57][58][59]. For recent reviews on modified gravity theories, see, for instance, [60][61][62][63][64].…”

Section: Introductionmentioning

confidence: 99%

Analysis with observational constraints in $$ \Lambda $$ Λ -cosmology in f(R, T) gravity

et al. 2018

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An exact cosmological solution of Einstein's field equations (EFEs) is derived for a dynamical vacuum energy in f (R, T) gravity for Friedmann-Lemaitre-Robertson-Walker (FLRW) space-time. A parametrization of the Hubble parameter is used to find a deterministic solution of the EFE. The cosmological dynamics of our model is discussed in detail. We have analyzed the time evolution of the physical parameters and obtained their bounds analytically. Moreover, the behavior of these parameters are shown graphically in terms of the redshift 'z'. Our model is consistent with the formation of structure in the Universe. The role of the f (R, T) coupling constant λ is discussed in the evolution of the equation of state parameter. The statefinder and Om diagnostic analysis is used to distinguish our model with other dark energy models. The maximum likelihood analysis has been reviewed to obtain the constraints on the Hubble parameter H 0 and the model parameter n by taking into account the observational Hubble data set H (z), the Union 2.1 compilation data set SNeIa, the Baryon Acoustic Oscillation data BAO, and the joint data set H (z) + SNeIa and H (z) + SNeIa + BAO. It is demonstrated that the model is in good agreement with various observations.

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Influence of modification of gravity on spherical wormhole models

Cited by 61 publications

References 53 publications

Wormhole models in f(R,T) gravity

Wormhole models in f(R,T) gravity

Wormholes in f(R) gravity with a noncommutative-geometry background

Analysis with observational constraints in $$ \Lambda $$ Λ -cosmology in f(R, T) gravity

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