Cosmological models with a hybrid scale factor in an extended gravity theory

Mishra, B.; Tripathy, S. K.; Tarai, Sankarsan

doi:10.1142/s0217732318500529

Cited by 62 publications

(37 citation statements)

References 73 publications

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“…But a more prominent approach to understanding this reversed pressure force is to modify the the Einstein theory of gravity known as general relativity (GR). To service this motivation, a lot of modifications of GR such as f (R) gravity, f (T ) gravity etc have been proposed [11][12][13]. Considering teleparallel equivalent of GR (TEGR) as a starting point, one can approach the modified gravity theory with matter-coupling.…”

Section: Introductionmentioning

confidence: 99%

A study of traversable wormhole solutions in extended teleparallel theory of gravity with matter coupling

et al. 2021

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This study is devoted to explore the physical aspects of wormhole geometry under embedded class-1 spacetime in $$f(T,\tau )$$ f ( T , τ ) gravity, where $$\tau $$ τ denotes the trace of the energy-momentum tensor and T is the torsion. We derive the embedded class-1 solutions by considering spherically symmetric static spacetime. The shape function is calculated in the framework of embedded class-1 spacetime. It is necessary to mention here that the calculated shape function can be used in other modified theories of gravity. To complete this study, we take diagonal and off-diagonal tetrad, and try to build a comparison by considering the validity region of energy conditions in embedded class-1 spacetime. The embedded surface diagram is given to understand the connection between the two different regions of spacetime. The validity regions of all the energy conditions are calculated. A detailed graphical analysis is provided for validity regions of all the energy conditions. The presence of exotic matter is confirmed in both the cases as the null energy condition is violated.

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Section: Introductionmentioning

confidence: 99%

A study of traversable wormhole solutions in extended teleparallel theory of gravity with matter coupling

et al. 2021

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“…In view of this, in the present work, we consider a hybrid scale factor ( as in Refs. [27,28]) that can simulate a transit universe from a decelerated phase to an accelerated phase.…”

Section: Basic Formalismmentioning

confidence: 99%

“…However, the belief that the universe has undergone a transition from a decelerated phase of expansion to an accelerated one requires the deceleration parameter to evolve from some positive values at remote past to negative values at late phase of cosmic evolution. Such a behaviour can be generated by a hybrid scale factor [27,28,46]. The hybrid scale factor behaves as power law in the early cosmic phase and as de Sitter type at late phase of cosmic acceleration.…”

Section: Model With a Hybrid Scale Factormentioning

confidence: 99%

Bianchi-V string cosmological model with dark energy anisotropy

Mishra

Tripathy

Ray

2018

Astrophys Space Sci

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The role of anisotropic components on the dark energy and the dynamics of the universe is investigated. An anisotropic dark energy fluid with different pressures along different spatial directions is assumed to incorporate the effect of anisotropy. One dimensional cosmic strings aligned along x-direction supplement some kind of anisotropy. Anisotropy in the dark energy pressure is found to evolve with cosmic expansion at least at late times. At an early phase, the anisotropic effect due to the cosmic strings substantially affect the dynamics of the accelerating universe.

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“…This is the subject of Section 2.1. This Bianchi type cosmological models have been employed in other contexts [15][16][17][18][19][20]. For example, in [16,18] are applied in scale invariant theory of gravitation, in [17,20] to extended gravity theory.…”

Section: Effective Modelmentioning

confidence: 99%

Cosmologies with Scalar Fields from Higher Dimensions Applied to Bianchi Type VIh=-1 Model: Classical and Quantum Solutions

Socorro

Sesma

Pimentel

2018

Advances in High Energy Physics

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We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. The corresponding action in four dimensions is similar to the action of K-essence theories. This approach is applied to anisotropic cosmological Bianchi type (ℎ=−1) model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. The classical Einstein field equations give us a hidden symmetry, corresponding to the equality between two radii B=C, which permits us to solve exactly the equations of motion. One relation between the scale factors (A,C) via the solutions is found. With this hidden symmetry, then we solve the FRW model, finding that the scale factor goes to B radii. Also the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology is solved, building a wavepacket when the scalar fields have a hyperbolic behavior, obtaining some qualitative results when we analyze the projection plane to the wall formed by the probability density. Bohm's formalism for this cosmological model is revisited too.

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Cosmological models with a hybrid scale factor in an extended gravity theory

Cited by 62 publications

References 73 publications

A study of traversable wormhole solutions in extended teleparallel theory of gravity with matter coupling

A study of traversable wormhole solutions in extended teleparallel theory of gravity with matter coupling

Bianchi-V string cosmological model with dark energy anisotropy

Cosmologies with Scalar Fields from Higher Dimensions Applied to Bianchi Type VIh=-1 Model: Classical and Quantum Solutions

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