Stability of the Einstein static universe in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>f</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>R</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:math>gravity

Böhmer, Christian G.; Hollenstein, Lukas; Lobo, Francisco S. N.

doi:10.1103/physrevd.76.084005

Cited by 146 publications

(106 citation statements)

References 65 publications

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“…Our results and general formulae are valid for any generic form of the function f (R). Our approach allows us to verify results previously derived based on specific forms of f (R), see [23]. Furthermore, we were able to reconcile the results of [23] and [24], which at first glance seem to be contradictory.…”

Section: Discussionsupporting

confidence: 66%

“…[22,23]. In the latter paper, it was found that stable solutions do exist which were unstable in general relativ-ity.…”

Section: Introductionmentioning

confidence: 93%

“…For instance, in [24] it was noted that that there exists only one functional form of f (R) that admits an Einstein static universe. On the other hand, in [23] the stability was analyzed for a model of a different type. Both findings seem to be inconsistent at first glance, however, in this paper we are able to reconcile all previous results and show their consistency.…”

Section: Introductionmentioning

confidence: 99%

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Einstein static universes are unstable in genericf(R)models

Seahra

Böhmer

2009

Phys. Rev. D

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We study Einstein static universes in the context of generic f (R) models. It is shown that Einstein static solutions exist for a wide variety of modified gravity models sourced by a barotropic perfect fluid with equation of state w = p/ρ, but these solutions are always unstable to either homogeneous or inhomogeneous perturbations. Our general results are in agreement with specific models investigated in that past. We also discuss how our techniques can be applied to other scenarios in f (R) gravity.

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Section: Discussionsupporting

confidence: 66%

“…[22,23]. In the latter paper, it was found that stable solutions do exist which were unstable in general relativ-ity.…”

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Einstein static universes are unstable in genericf(R)models

Seahra

Böhmer

2009

Phys. Rev. D

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“…Extending our analysis to modified gravity theories we find that a new minimum in the effective potential appears corresponding to a stable ESU. These results are in broad agreement with earlier studies which also pointed out the appearance of an ESU in the context of extensions to GR [13,14,34]; also see [35].…”

Section: Discussionsupporting

confidence: 92%

Emergent cosmology revisited

Bag

Sahni

Shtanov

et al. 2014

J. Cosmol. Astropart. Phys.

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Abstract. We explore the possibility of emergent cosmology using the effective potential formalism. We discover new models of emergent cosmology which satisfy the constraints posed by the cosmic microwave background (CMB). We demonstrate that, within the framework of modified gravity, the emergent scenario can arise in a universe which is spatially open/closed. By contrast, in general relativity (GR) emergent cosmology arises from a spatially closed pasteternal Einstein Static Universe (ESU). In GR the ESU is unstable, which creates fine tuning problems for emergent cosmology. However, modified gravity models including Braneworld models, Loop Quantum Cosmology (LQC) and Asymptotically Free Gravity result in a stable ESU. Consequently, in these models emergent cosmology arises from a larger class of initial conditions including those in which the universe eternally oscillates about the ESU fixed point. We demonstrate that such an oscillating universe is necessarily accompanied by graviton production. For a large region in parameter space graviton production is enhanced through a parametric resonance, casting serious doubts as to whether this emergent scenario can be past-eternal.

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“…These different ( ) f R -gravity theories have also been discussed in the stability conditions [58]- [62], inflationary epoch [63], compatibility with solar-system tests and galactic data [64]- [72] and the late-time cosmological evolution [73]- [80]. Additional constraints to ( ) f R theories may be caused by imposing the so-called energy conditions [81] …”

Section: Introductionmentioning

confidence: 99%

Phantom and Quintessence Fields Coupled to Scalar Curvature in General <i>f(R)</i> Gravity Theory

Zhang¹,

Huang²

2017

JMP

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This paper reviews the development of f(R) gravity theory and Phantom and Quintessence fields. Specifically, we present a new general action of f(R) gravity and Phantom and Quintessence fields coupled to scalar curvature. Then, we deduce Euler-Lagrange Equations of different fields, matter tensor and effective matter tensor. Additionally, this paper obtains the general pressure, density and speed sound of the new general field action, and investigates different cosmological evolutions with inflation. Further, this paper investigates a general f(R) gravity theory with a general matter action and obtains the different field equations, general matter tensor and effective matter tensor. Besides, this paper obtains the effective Strong Energy Condition (SEC) and effective Null Energy Condition (NEC). Then, we prove that when f(R) approaches to R, the effective SEC and the effective NEC approach to the usual SEC and the usual NEC, respectively. Finally, this paper presents a general action of f(R) gravity, Quintessence and Phantom fields and their applications.

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Stability of the Einstein static universe inf(R)gravity

Cited by 146 publications

References 65 publications

Einstein static universes are unstable in genericf(R)models

Einstein static universes are unstable in genericf(R)models

Emergent cosmology revisited

Phantom and Quintessence Fields Coupled to Scalar Curvature in General <i>f(R)</i> Gravity Theory

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Stability of the Einstein static universe inf(R)gravity

Cited by 146 publications

References 65 publications

Einstein static universes are unstable in genericf(R)models

Einstein static universes are unstable in genericf(R)models

Emergent cosmology revisited

Phantom and Quintessence Fields Coupled to Scalar Curvature in General &lt;i&gt;f(R)&lt;/i&gt; Gravity Theory

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Product

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Phantom and Quintessence Fields Coupled to Scalar Curvature in General <i>f(R)</i> Gravity Theory