Cyclic cosmology in modified gravity

Pavlović, Petar; Sossich, Marko

doi:10.1103/physrevd.95.103519

Cited by 25 publications

(26 citation statements)

References 102 publications

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“…Though the theory stood the test of time and has diverse applications in physical cosmology, it cannot explain the biggest problem in physical cosmology, i.e the nature of cosmological constant. The acceleration of the universe at the present epoch cannot be explained without invoking new forms of matter and/or energy [6]. There are two possible routes to tackle this outstanding problem-firstly, we can convince ourselves that we are living in a universe with a scalar field or "cosmological constant (Λ)" which accelerates the universe on largest scales.…”

Section: Introductionmentioning

confidence: 99%

Bouncing scenario in f(R,T) gravity

2020

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In the context of bouncing scenario in a four dimensional Friedmann-Lemaître-Robertson-Walker geometry, we address two bouncing cosmological model within f (R, T ) = R+2λT gravity formalism. The exact solution of f (R, T ) gravity field equations is obtained by employing some special kind of scale factors which provides two bouncing scenarios namely matter bounce and super bounce respectively. In addition we have studied the dynamical behavior of equation of state parameter and energy conditions for the models. We found an effective role of coupling parameter λ in obtaining bouncing scenario as compared to the parameters of the bouncing scale factors. PACS numbers: 04.50.kd In the paradigm of big bang cosmology, our universe emerged out of a singularity, is finite in time and space and is around 13.7 billion years young. Though the historic discovery of CMB

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Section: Introductionmentioning

confidence: 99%

Bouncing scenario in f(R,T) gravity

2020

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“…Additionally, and interestingly, some of the models allow a singularity free scale factor. The realization of cyclic universe in this context [42] is a new addition in the literature.…”

Section: Discussionmentioning

confidence: 99%

Exact solutions, finite time singularities and non-singular universe models from a variety of Λ(t) cosmologies

Pan

2018

Mod. Phys. Lett. A

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Cosmological models with time dependent Λ (read as Λ(t)) have been investigated widely in the literature. Models that solve background dynamics analytically, are of special interest. Additionally, the allowance of past or future singularities at finite cosmic time in a specific model signals for a generic test on its viabilities with the current observations. Following these, in this work we consider a variety of Λ(t) models focusing on their evolutions and singular behaviour. We found that a series of models in this class can be exactly solved when the background universe is described by a spatially flat Friedmann-Lemaître-Robertson-Walker (FLRW) line element. The solutions in terms of the scale factor of the FLRW universe offer different universe models, such as power law expansion, oscillating, and the singularity free universe as well. However, we also noticed that a large number of models in this series permits past or future cosmological singularities at finite cosmic time. At last we close the work with a note that the avoidance of future singularities is possible for certain models under some specific restrictions.PACS numbers: 98.80.-k, 95.36.+x

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“…General relativity predicts a spacetime singularity for the beginning of the universe [1][2][3][4], as it is no longer valid and so there are some alternative theories to standard big bang cosmology [5][6][7][8][9][10][11][12][13]. Many attempts have been done to resolve this singularity problem through the modified general relativity theory [14][15][16][17][18], although it may be resolved via string theory and/or loop quantum cosmology [19,20] as some candidates for a quantum theory of gravity [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Bouncing universe of entropy-corrected Friedmann equations

Salehi

Mahmoudi-Fard

2018

Eur. Phys. J. C

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In this paper, we investigate the possibility of obtaining bouncing-oscillating solution in modified Friedmann equations with logarithmic entropy corrected,A , for positive, negative and zero values of (α, β) pre-factors and all kinds of curved universes. The results are argued using the dynamical system techniques and by employing the phase plane analysis for full classification of the nonsingular evolutions. Our analysis indicates that it is possible to have an oscillating universe as well as a bounce universe for k = 1 and k = − 1 curvatures. In k = 1 case, both positive and negative values of α and β can make bouncing-oscillating solution, while in k = − 1 case, only the positive value of α with negative value of β can make a bounce. Also the flat universe have no bounce solution.

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Cyclic cosmology in modified gravity

Cited by 25 publications

References 102 publications

Bouncing scenario in f(R,T) gravity

Bouncing scenario in f(R,T) gravity

Exact solutions, finite time singularities and non-singular universe models from a variety of Λ(t) cosmologies

Bouncing universe of entropy-corrected Friedmann equations

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