The Abc of Cosmography

Bolotin, Yu. L.; Zazunov, L.G.; Konchatnyi, M.; Lemets, O. A.

doi:10.18524/1810-4215.2017.30.114129

Cited by 6 publications

(8 citation statements)

References 6 publications

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“…Applying the field equations of the first case for the three different values of β and for w = 1, −1, 1 3 and w = 0, revealed that the relationships between the values of β and the types of future singularities were the same as those under the FRW gravity (Figs. 3,4,5,6,7,8). In the case f = R + αRR µν T µν , however, the study of field equations and the singularities which might happen in the future of the universe unfolded interesting result.…”

Section: Discussionmentioning

confidence: 99%

Late time dynamics of $f(R, T, R_{μν}T^{μν})$ gravity

Abchouyeh,

Mirza,

Shahidi

et al. 2020

Preprint

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Dynamical behavior and future singularities of f (R, T, Rµν T µν ) gravitational theory are investigated. This gravitational model is a more complete form of the f (R, T ) gravity which can offer new dynamics for the universe. We investigate this gravitational theory for the case f = R + αRµν T µν using the method of autonomous dynamical systems and by assuming an interaction between matter and dark energy. The fixed points are identified and the results are consistent with standard cosmology and show that for small α, the radiation dominated era is an unstable fixed point of the theory and the universe will continue its procedure toward matter era which is a saddle point of the theory and allows the evolution to dark energy dominated universe. Finally the dark energy dominated epoch is a stable fixed point and will be the late time attractor for the universe. We also consider future singularities for the two f = R + αRµν T µν and f = R + αRRµν T µν cases and for w = 0, 1 3 , 1 and −1. Our results show that for the case of f = R + αRµν T µν , the future singularities of the universe will happen in the same condition as do for the Einstein-Hilbert FRW universe. However, a new type of singularity is obtained for f = R + αRRµν T µν that is captured by t → ts; a → as; ρ → ∞; and |p| → 0.

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Section: Discussionmentioning

confidence: 99%

Late time dynamics of $f(R, T, R_{μν}T^{μν})$ gravity

Abchouyeh,

Mirza,

Shahidi

et al. 2020

Preprint

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“…The H, q, j, s are kinematical quantities, which are directly extracted from the spacetime. The kinematic quantities are defined as [56,57]…”

Section: Cosmographic Parametersmentioning

confidence: 99%

Dynamics in Interacting Scalar-Torsion Cosmology

Paliathanasis

2021

Universe

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In a spatially flat Friedmann–Lemaître–Robertson–Walker background space, we consider a scalar-torsion gravitational model which has similar properties to the dilaton theory. This teleparallel model is invariant under a discrete transformation similar to the Gasperini–Veneziano duality transformation. Moreover, in the gravitational action integral, we introduce the Lagrangian function of a pressureless fluid source which is coupled to the teleparallel dilaton field. This specific gravitational theory with interaction in the dark sector of the universe was investigated by using methods of the dynamical system analysis. We calculate that the theory provides various areas of special interest for the evolution of the cosmological history. Inflationary scaling solutions and the de Sitter universe are recovered. Furthermore, we calculate that there exist an attractor which provides a stable solution where the two fluid components, the scalar field and the pressureless matter, contribute in the cosmological fluid. This solution is of special interest because it can describe the present epoch. Finally, the qualitative evolution of the cosmographic parameters is discussed.

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“…Under the background of the homogeneous and isotropic universe characterized by the FLRW universe, one can define the kinematical quantities as [54,55]…”

Section: Evolution Of the Cosmographic Parametersmentioning

confidence: 99%

Dynamics of quintessence in generalized uncertainty principle

et al. 2020

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We investigate the quintessence scalar field model modified by the generalized uncertainty principle in the background of a spatially flat homogeneous and isotropic universe. By performing a dynamical system analysis we examine the nature of the critical points and their stability for two potentials, one is the exponential potential and the other is a general potential. In the case of an exponential potential, we find some new critical points for this modified quintessence scenario that describe the de Sitter universes, and these critical points do not appear in the standard quintessence model with an exponential potential. This is one of the main results of this work. Now for the general potential our analysis shows that the physical properties of the critical points remain exactly the same as for the exponential potential which means that within this modified quintessence scenario all kind of potentials have same behaviour. This kind of result is completely new in cosmology because with the change of the potential, differences are usually expected in all respect.

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The Abc of Cosmography

Cited by 6 publications

References 6 publications

Late time dynamics of $f(R, T, R_{μν}T^{μν})$ gravity

Late time dynamics of $f(R, T, R_{μν}T^{μν})$ gravity

Dynamics in Interacting Scalar-Torsion Cosmology

Dynamics of quintessence in generalized uncertainty principle

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