Evolution of density perturbations 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

Carloni, Sante; Dunsby, Peter K. S.; Troisi, A.

doi:10.1103/physrevd.77.024024

Cited by 176 publications

(166 citation statements)

References 30 publications

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“…The cosmologies of various models are studied in [326][327][328][329][330][331][332][333][334]. Additionally, the behavior of perturbations and large-scale structure has been carefully studied in f (R) gravity [335][336][337][338][339][340][341][342][343][344][345][346]. One intriguing possibility is that modifications of the f (R) type could explain cosmic inflation and late-time acceleration in a unified way, which is investigated in [347][348][349][350][351][352][353][354][355].…”

Section: Example: F (R) Gravitymentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Example: F (R) Gravitymentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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“…Also, they must provide cosmological perturbations compatible with cosmological constraints from cosmic microwave background and large scale structure. The problem of cosmological perturbations in this modified theory and their consequences have widely been discussed in literature, e.g., (Hwang and Noh 2006;Carroll et al 2006;Carloni et al 2008;Tsujikawa et al 2008). Since the lagrangian R + f (R) is analytic at R = 0, so the Schwarzschild and other important GR solutions (without cosmological constant) are also the solutions of f (R) gravity (de la Cruz-Dombrize and Dobado 2006).…”

Section: Introductionmentioning

confidence: 99%

“…The problem of dynamical instability is closely related to the structure formation and evolution of self-gravitating objects. A pioneer work in this direction was done by Chandrasekhar (Chandrasekhar 1964). Afterwards, this issue has been investigated by many authors for adiabatic, non-adiabatic, anisotropic and shearing viscous fluids (Herrera et al 1989;Chan et al 1989;Chan et al 1994;Chan et al 1993;Herrera et al, arXiv/1010.1518.…”

Section: Introductionmentioning

confidence: 99%

Newtonian and post Newtonian expansionfree fluid evolution in f(R) gravity

Sharif¹,

Kausar²

2011

Astrophys Space Sci

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We consider a collapsing sphere and discuss its evolution under the vanishing expansion scalar in the framework of f (R) gravity. The fluid is assumed to be locally anisotropic which evolves adiabatically. To study the dynamics of the collapsing fluid, Newtonian and post Newtonian regimes are taken into account. The field equations are investigated for a well-known f (R) model of the form R + δR 2 admitting Schwarzschild solution. The perturbation scheme is used on the dynamical equations to explore the instability conditions of expansionfree fluid evolution. We conclude that instability conditions depend upon pressure anisotropy, energy density and some constraints arising from this theory.

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“…As a matter of fact, let remind that R n gravities are severely constrained by solar system tests [28] as well as by the evolution baryon acoustic oscillations and scalar and tensor perturbations [29].…”

Section: Null Geodesicsmentioning

confidence: 99%

The Raychaudhuri equation in homogeneous cosmologies

Albareti

Cembranos

Cruz-Dombriz

et al. 2014

J. Cosmol. Astropart. Phys.

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In this work we address the issue of studying the conditions required to guarantee the Focusing Theorem for both null and timelike geodesic congruences by using the Raychaudhuri equation. In particular we study the case of Friedmann-Robertson-Walker as well as more general Bianchi Type I spacetimes. The fulfillment of the Focusing Theorem is mandatory in small scales since it accounts for the attractive character of gravity. However, the Focusing Theorem is not satisfied at cosmological scales due to the measured negative deceleration parameter. The study of the conditions needed for congruences convergence is not only relevant at the fundamental level but also to derive the viability conditions to be imposed on extended theories of gravity describing the different expansion regimes of the universe. We illustrate this idea for f (R) gravity theories.PACS numbers: 04.50. Kd, 98.80.Jk, 95.36.+x

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Evolution of density perturbations inf(R)gravity

Cited by 176 publications

References 30 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

Newtonian and post Newtonian expansionfree fluid evolution in f(R) gravity

The Raychaudhuri equation in homogeneous cosmologies

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