Unification of a bounce with a viable dark energy era in Gauss-Bonnet gravity

Odintsov, Sergei D.; Oikonomou, V. K.; Fronimos, F. P.; Fasoulakos, K. V.

doi:10.1103/physrevd.102.104042

Cited by 55 publications

(35 citation statements)

References 66 publications

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“…The search for stable de Sitter solutions is important for f (R, G) models that explain the late-time accelerated expansion of the Universe [29,59,60,62,65,66]. A generic f (R, G) action can be transformed into one linear in R and G by including of two scalar fields, whereas the proposed special type of such models describing by action (29) can be linearized in R and G by including of one scalar field without kinetic term.…”

Section: Discussionmentioning

confidence: 99%

“…The cosmological models with the Gauss-Bonnet term are motivated by the string theory [30][31][32][33][34][35][36][37] and are actively used for describing of both the early Universe evolution (inflation) [25][26][27][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] and the current dark energy dominated epoch [28][29][30][31]36,37,[58][59][60][61][62][63][64][65][66]. Note that both stages of the Universe evolution are characterized by the quasi de Sitter accelerated expansion of the Universe.…”

Section: Introductionmentioning

confidence: 99%

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De Sitter Solutions in Einstein–Gauss–Bonnet Gravity

Vernov

Pozdeeva

2021

Universe

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De Sitter solutions play an important role in cosmology because the knowledge of unstable de Sitter solutions can be useful to describe inflation, whereas stable de Sitter solutions are often used in models of late-time acceleration of the Universe. The Einstein–Gauss–Bonnet gravity cosmological models are actively used both as inflationary models and as dark energy models. To modify the Einstein equations one can add a nonlinear function of the Gauss–Bonnet term or a function of the scalar field multiplied on the Gauss–Bonnet term. The effective potential method essentially simplifies the search and stability analysis of de Sitter solutions, because the stable de Sitter solutions correspond to minima of the effective potential.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

De Sitter Solutions in Einstein–Gauss–Bonnet Gravity

Vernov

Pozdeeva

2021

Universe

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“…and the present time scale factor, that is, at z ¼ 0, is assumed to be equal to unity. The statefinder we shall use is the function y H ðzÞ [15,17,[132][133][134][135],…”

Section: Early and Late Dark Energy Erasmentioning

confidence: 99%

Unifying inflation with early and late dark energy epochs in axion F(R) gravity

Oikonomou

2021

Phys. Rev. D

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121

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We provide a theoretical model of FðRÞ gravity in which it is possible to describe in a unified way inflation, an early and a late dark energy era, in the presence of a light axion particle which plays the role of the dark matter component of the Universe. Particularly, the early time phenomenology is dominated by an R 2 term, while the presence of the other terms fðRÞ ensure the occurrence of the early and late-time dark energy eras. The inflationary phenomenology is compatible with the Planck 2018 data for inflation, while the late-time dark energy era is compatible with the Planck 2018 constraints on the cosmological parameters. Also, the model exhibits an early dark energy era, at z ∼ 2.5 approximately, followed by a deceleration era, which starts at approximately z ∼ 1.5, which in turn is followed by a late-time dark energy era for redshifts z ∼ 0.5, which lasts for approximately 5 billion years up to present time. A notable feature of our model is that the dark energy era is free from dark energy oscillations, at least in the redshift interval z ¼ ½0; 10. In addition, we also discuss several features related to observational data at z ∼ 2.34, at which redshift intricate observational data exist in the literature. Moreover, the numerical code for the dark energy phenomenology, written in PYTHON3, is presented in the end of the article. Finally, the model has another interesting characteristic, a sudden jump of the value of the Hubble rate in the redshift interval z ∼ ½2; 2.6 where its value suddenly increases and then decreases until z ∼ 0.

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“…The main premise is to follow the steps as in Ref [53,54] where for a general modified theory of gravity, dark energy obtains a fundamental definition. Instead of being an arbitrary perfect fluid now dark energy serves as the effect of all geometric terms participating initially in the gravitational action that rectify Einstein's description.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Coupling Corrected Einstein-Gauss-Bonnet Gravity Late-Time Phenomenology

Fronimos¹

2021

Preprint

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In this short note we present the dynamics of a general scalar-tensor model, and in particular a scalar Einstein-Gauss-Bonnet model with a non-minimal coupling between gravity and the kinetic term of the scalar field. For the sake of simplicity two f (R) models are studied separately, an exponential and a power-law, accompanied by either an exponential or quartic scalar potential and a strictly exponential Gauss-Bonnet scalar coupling function known for being a suitable candidate for describing both the early and the late time. By introducing the general framework of a late-time study for an arbitrary scalar-tensor model, we find that the aforementioned models are capable of producing compatible with the Planck data observations and are in a relatively good agreement with the ΛCDM model and the GW170817 event as the tensor perturbation velocity is equal to unity in natural units for the whole are of values of redshift studied if certain parameters are properly designated. A brief comment on the appearance of dark energy oscillations which appear for the case of power-law f (R) and the overall viability of the model is also made.

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Unification of a bounce with a viable dark energy era in Gauss-Bonnet gravity

Cited by 55 publications

References 66 publications

De Sitter Solutions in Einstein–Gauss–Bonnet Gravity

De Sitter Solutions in Einstein–Gauss–Bonnet Gravity

Unifying inflation with early and late dark energy epochs in axion F(R) gravity

Kinetic Coupling Corrected Einstein-Gauss-Bonnet Gravity Late-Time Phenomenology

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