Cosmological constraints on<i>f</i>(<i>G</i>) dark energy models

Zhou, Shuang-Yong; Copeland, Edmund J.; Saffin, Paul M.

doi:10.1088/1475-7516/2009/07/009

Cited by 119 publications

(67 citation statements)

References 82 publications

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“…It is worth noting that, the critical lines are obtained from studying dynamical behavior of f (T ) gravity theories without any assumptions in [13] are in agreement with the relations between dimensionless variables Table 2. The viability condition for the f (R) and f (G) models have investigated in [14]- [16].…”

Section: Introductionmentioning

confidence: 99%

Canf(T) gravity theories mimic ΛCDM cosmic history

Setare

Mohammadipour

2013

J. Cosmol. Astropart. Phys.

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Recently the teleparallel Lagrangian density described by the torsion scalar T has been extended to a function of T. The f (T ) modified teleparallel gravity has been proposed as the natural gravitational alternative for dark energy to explain the late time acceleration of the universe. In order to reconstruct the function f (T ) by demanding a background ΛCDM cosmology we assume that, (i) the background cosmic history provided by the flat ΛCDM (the radiation ere with ω ef f = 1 3 , matter and de Sitter eras with ω ef f = 0 and ω ef f = −1, respectively) (ii) the radiation dominate in the radiation era with Ω 0r = 1 and the matter dominate during the matter phases when Ω 0m = 1. We find the cosmological dynamical system which can obey the ΛCDM cosmic history. In each era, we find a critical lines that, the radiation dominated and the matter dominated are one points of them in the radiation and matter phases, respectively. Also, we drive the cosmologically viability condition for these models. We investigate the stability condition with respect to the homogeneous scalar perturbations in each era and we obtain the stability conditions for the fixed points in each eras. Finally, we reconstruct the function f (T ) which mimics cosmic expansion history.

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Section: Introductionmentioning

confidence: 99%

Canf(T) gravity theories mimic ΛCDM cosmic history

Setare

Mohammadipour

2013

J. Cosmol. Astropart. Phys.

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“…The matter action S m is the one which induces the energymomentum tensor T μν . We focus our attention on the metric formalism where the variation of the action (5) with respect to the metric tensor yields within the minimum principle the following general equation of motion [50][51][52][53][54]:…”

Section: Formalism Of F (G) Gravity and Unimodular Equations Of Motionmentioning

confidence: 99%

Unimodular f(G) gravity

Nassur¹,

Ainamon²,

Houndjo³

et al. 2017

Eur. Phys. J. C

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In this paper we study a modified version of unimodular general relativity in the context of f (G), G denoting the Gauss-Bonnet invariant. We focus on Bianchi-type I and Friendmann-Robertson-Walker universes and search for unimodular f (G) models according to the de Sitter and power-law solutions. Assuming unimodular f (G) gravity as a perfect fluid and making use of the slow-roll parameters, the inflationary model has been reconstructed in concordance with the Planck observational data. Moreover, we investigate the realization of the bounce and loop quantum cosmological ekpyrotic paradigms. Assuming suitable and appropriate scale factors, unimodular f (G) models able to reproduce superbounce and ekpyrotic scenarios have been reconstructed.

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“…Similarly, f (T ) gravity is also a modified theory, which has attracted the attention of theoretical physicists gain insight in acceleration and regular thermal expansion of the late-time universe by assuming an alternative for the cosmological constant, where f (T ) is a function of the torsion scalar [14]. An endeavor was made by combining R and G in a bivariate function f (R, G) [15][16][17][18][19][20][21][22]. The function f (R, G) provides a foundation for the double inflationary scenario [23].…”

Section: Introductionmentioning

confidence: 99%

Physical attributes of anisotropic compact stars in f(R, G) gravity

Shamir

Zia

2017

Eur. Phys. J. C

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Modified gravity is one of the potential candidates to explain the accelerated expansion of the universe. Current study highlights the materialization of anisotropic compact stars in the context of f (R, G) theory of gravity. In particular, to gain insight in the physical behavior of three stars namely, Her X 1, SAX J 1808-3658 and 4U 1820-30, energy density, and radial and tangential pressures are calculated. The f (R, G) gravity model is split into a Starobinsky like f (R) model and a power law f (G) model. The main feature of the work is a 3-dimensional graphical analysis in which, anisotropic measurements, energy conditions and stability attributes of these stars are discussed. It is shown that all three stars behave as usual for positive values of the f (G) model parameter n.

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Cosmological constraints onf(G) dark energy models

Cited by 119 publications

References 82 publications

Canf(T) gravity theories mimic ΛCDM cosmic history

Canf(T) gravity theories mimic ΛCDM cosmic history

Unimodular f(G) gravity

Physical attributes of anisotropic compact stars in f(R, G) gravity

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