Stability of the Einstein static universe in f(R, T) gravity

Shabani, Hamid; Ziaie, Amir Hadi

doi:10.1140/epjc/s10052-017-4597-z

Cited by 129 publications

(74 citation statements)

References 162 publications

(172 reference statements)

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“…It has been studied in several astrophysical and cosmological aspects, by assuming different choices for the arbitrary function of R and T ; see [12][13][14], for instance.…”

Section: Introductionmentioning

confidence: 99%

Wormholes in $$R^2$$ R 2 -gravity within the f(R, T) formalism

2018

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We propose, as a novelty in the literature, the modeling of wormholes within a particular case of f (R, T ) gravity, namely f (R, T ) = R + α R 2 + λT , with R and T being the Ricci scalar and trace of the energy-momentum tensor, respectively, while α and λ are constants. Although such a functional form application can be found in the literature, those concern compact astrophysical objects, such that no wormhole analysis has been done so far. The quadratic geometric and linear material corrections of this theory render the matter content of the wormhole remarkably able to obey the energy conditions.

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“…It has been studied in several astrophysical and cosmological aspects, by assuming different choices for the arbitrary function of R and T ; see [12][13][14], for instance.…”

Section: Introductionmentioning

confidence: 99%

Wormholes in $$R^2$$ R 2 -gravity within the f(R, T) formalism

2018

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“…In GR, this was reconsidered, and it was found that the Einstein static universe can be stable against small inhomogeneous vector and tensor perturbations as well as adiabatic scalar density perturbations if the universe contains a perfect fluid with w = c 2 s > 1/5 [25,26,31]. Of course, the stability of the Einstein static universe has also been extensively studied in many modified gravities, for example, loop quantum cosmology [32], f (R) theory [33][34][35], f (T ) theory [36,37], modified Gauss-Bonnet gravity [38,39], Brans-Dicke theory [40][41][42][43], Horava-Lifshitz theory [44][45][46], massive gravity [47,48], braneworld scenario [49][50][51], Einstein-Cartan theory [52], f (R, T ) gravity [53], hybrid metric-Palatini gravity [54] and so on [55][56][57][58][59][60][61][62]. We refer to e.g.…”

Section: Introductionmentioning

confidence: 99%

Stability of the Einstein static universe in Eddington-inspired Born-Infeld theory

Hao

2017

Phys. Rev. D

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By considering the realization of the emergent universe scenario in Eddington-inspired Born-Infeld (EiBI) theory, we study the stability of the Einstein static universe filled with perfect fluid in EiBI theory against both the homogeneous and inhomogeneous scalar perturbations in this work. We find that in both the spatially flat and closed cases, the emergent universe scenario is no longer viable, since the Einstein static universe cannot be stable against both the homogeneous and inhomogeneous scalar perturbations simultaneously. However, the emergent universe scenario survives in the spatially open case, while the Einstein static universe can be stable under some conditions.

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“…to t. Taking f (R, T ) = R + αR 2 + 2λT and using Eqs. (7), (18), (19) in Eq. (15), we get the following field equations…”

Section: Cosmological Dynamics Of the Universementioning

confidence: 99%

Cosmological aspects of a hyperbolic solution in f(R,T) gravity

et al. 2019

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This article deals with a cosmological scenario in f (R, T ) gravity for a flat FLRW model of the universe. We consider the f (R, T ) function as f (R) + f (T ) which starts with a quadratic correction of the geometric term f (R) having structure f (R) = R + αR 2 , and a linear matter term f (T ) = 2λT . To achieve the solution of the gravitational field equations in the f (R, T ) formalism, we take the form of a geometrical parameter, i.e. scale factor a(t) = sinh 1 n (βt) [31], where β and n are model parameters. An eternal acceleration can be predicted by the model for 0 < n < 1, while the cosmic transition from the early decelerated phase to the present accelerated epoch can be anticipated for n ≥ 1. The obtained model facilitate the formation of structure in the Universe according to the Jeans instability condition as our model transits from radiation dominated era to matter dominated era. We study the varying role of the equation of state parameter ω. We analyze our model by studying the behavior of the scalar field and discuss the energy conditions on our achieved solution. We examine the validity of our model via Jerk parameter, Om diagnostic, Velocity of sound and Statefinder diagnostic tools. We investigate the constraints on the model parameter n and H0 (Hubble constant) using some observational datasets: SN eIa dataset, H(z) (Hubble parameter) dataset, BAO (Baryon Acoustic Oscillation data) and their combinations as joint observational datasets H(z) + SN eIa and H(z) + SN eIa + BAO. It is testified that the present study is well consistent with these observations. We also perform some cosmological tests and a detailed discussion of the model. PACS number: 98.80 cqIn the above equation, R ij is the Ricci tensor, R the Ricci scalar, g ij the covariant metric tensor of order 2, Λ the cosmological constant, G the gravitational constant, c indicates the speed of the light, and T ij the energymomentum-tensor (EMT). Despite the fact that general relativity (GR) is extremely well tested, alternatives are always present. According to observations, 95% of the matter content of the Universe is unexplored. GR has several problems, as the problem of initial big-bang spacetime singularity [1-3] and it is not yet quantised. GR has to be reconciled with quantum physics to discuss quantum effects. GR together with quantum physics forms the backbone of modern physics. The ΛCDM model of the cosmology is quite successful, but there remain several unresolved issues such as the fine tuning problem [4]. Hence it is worthwhile to examine alternative theories of gravity.Amongst large range of modified theories of gravity, f (R) gravity [5] is considered as an interesting alternative. A more general function of R i.e. f (R) is considered in the Einstein-Hilbert action . An intensively study on f (R) gravity seems to indicate that it is an improvement over GR [6][7][8]. It can also explain both phases of cosmic acceleration even in the absence of Λ (early and late times) [9]. f (R) gravity behaves extremely well on large scales...

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Stability of the Einstein static universe in f(R, T) gravity

Cited by 129 publications

References 162 publications

Wormholes in $$R^2$$ R 2 -gravity within the f(R, T) formalism

Wormholes in $$R^2$$ R 2 -gravity within the f(R, T) formalism

Stability of the Einstein static universe in Eddington-inspired Born-Infeld theory

Cosmological aspects of a hyperbolic solution in f(R,T) gravity

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