Scalar field and time varying cosmological constant in f ( R , T ) gravity for Bianchi type-I universe

Singh, G. P.; Bishi, Binaya K.; Sahoo, P. K.

doi:10.1016/j.cjph.2016.04.010

Cited by 32 publications

(8 citation statements)

References 62 publications

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“…In another work, they have explored the evolutionary behaviour of compact objects [21]. Recently, Sahoo and his collaborators have extensively investigated different aspects of this modified gravity theory and have reconstructed some f (R, T ) cosmological models for anisotropic universes [22][23][24][25][26][27]. Some higher dimensional models have also been constructed in recent times in f (R, T ) theory [23,28].…”

Section: Introductionmentioning

confidence: 99%

Cosmic transit and anisotropic models in f(R,T) gravity

Sahu¹,

Tripathy²,

Sahoo³

et al. 2017

Chinese Journal of Physics

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Accelerating cosmological models are constructed in a modified gravity theory dubbed as f (R, T ) gravity at the backdrop of an anisotropic Bianchi type-III universe. f (R, T ) is a function of the Ricci scalar R and the trace T of the energy-momentum tensor and it replaces the Ricci scalar in the Einstein-Hilbert action of General Relativity. The models are constructed for two different ways of modification of the Einstein-Hilbert action. Exact solutions of the field equations are obtained by a novel method of integration. We have explored the behaviour of the cosmic transit from an decelerated phase of expansion to an accelerated phase to get the dynamical features of the universe. Within the formalism of the present work, it is found that, the modification of the Einstein-Hilbert action does not affect the scale factor. However the dynamics of the effective dark energy equation of state is significantly affected.

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Section: Introductionmentioning

confidence: 99%

Cosmic transit and anisotropic models in f(R,T) gravity

Sahu¹,

Tripathy²,

Sahoo³

et al. 2017

Chinese Journal of Physics

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“…Zubair and Ali Hassan [21] studied the Bianchi types I and III and Kantowski-Sachs spacetimes in a unified way by assuming that the expansion scalar is proportional to the shear scalar and also that the derivative of f (R,T) with respect to R is proportional to the scale factor. In Singh et al [22], an LRS model with a scalar field was considered, as well as power-law and exponential forms for the scale factor and scalar field. A string cosmological model was derived by Sahoo [23] utilizing a constant deceleration parameter and the ansatz that the scalar expansion is proportional to the shear scalar.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Cosmological Model in a Modified Theory of Gravitation

Tiwari¹,

Беешам

Mishra

et al. 2021

Universe

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Current observations indicate that, on a large enough scale, the universe is homogeneous and isotropic. However, this does not preclude the possibility of some anisotropy having occurred during the early stages of the evolution of the universe, which could then have been damped out later. This idea has aroused interest in the Bianchi models, which are homogeneous but anisotropic. Secondly, there is much interest in modified gravity these days due to the problems that the usual ΛCDM model faces in general relativity. Hence, in this paper, a study was conducted on the Bianchi type-I cosmological model in f(R,T)-modified gravity. Following some ideas from cosmography, a specific form of the deceleration parameter was assumed, leading to a model that exhibited a transition from early deceleration to late-time acceleration. The derived model approached isotropy at late times. The physical properties of the model were discussed, and expressions for the various parameters of the model were derived. It is also possible to make progress towards solving the cosmological constant problem, since in this model in f(R,T) gravity, a variable cosmological-type parameter arose, which was large early on but decreased to a constant value in later times.

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“…Accelerating cosmological models have been constructed by Sahu et al [48] in f (R, T ) modified gravity theory at the backdrop of an anisotropic Bianchi type-III universe. Sahoo and his collaborators have reconstructed some f (R, T ) cosmological models for anisotropic universes [49][50][51][52][53].…”

Section: Introductionmentioning

confidence: 99%

Charged strange star with Krori–Barua potential in f(R, T) gravity admitting Chaplygin equation of state

Bhar¹

2020

Eur. Phys. J. Plus

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In present paper a new compact star model in f (R, T ) gravity is obtained where R and T denote the Ricci scalar and the trace of energy-momentum tensor Tµν respectively. To develop the model we consider the spherically symmetric space-time along with anisotropic fluid distribution in presence of electric field with f (R, T ) = R + 2γT where γ is a small positive constant. We have used the Chaplygin equation of state to explore the stellar model. The field equations for f (R, T ) gravity have been solved by employing the Krori-Barua ansatz already reported in literature [J. Phys. A, Math. Gen. 8:508, 1975]. The exterior spacetime is described by Reissner-Nordström line element for smooth matching at the boundary. It is worthwhile to mention here that the values of all the constants involved with this model have been calculated for the strange stars 4U 1538-52 for different values of γ with the help of matching conditions. The acceptability of the model is discussed in details both analytically and graphically by studying the physical attributes of matter density, pressures, anisotropy factor, stability etc. We have also obtained the numerical values in tabular form for central density, surface density, central pressure and cental adiabatic index for different values of γ. The solutions of the field equations in Einstein gravity can be regained by simply putting γ = 0 to our solution. Moreover, the proposed model is shown to be physically admissible and corroborate with experimental observations on strange star candidates such as 4U 1538-52.

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Scalar field and time varying cosmological constant in f ( R , T ) gravity for Bianchi type-I universe

Cited by 32 publications

References 62 publications

Cosmic transit and anisotropic models in f(R,T) gravity

Cosmic transit and anisotropic models in f(R,T) gravity

Anisotropic Cosmological Model in a Modified Theory of Gravitation

Charged strange star with Krori–Barua potential in f(R, T) gravity admitting Chaplygin equation of state

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