Post-newtonian parameters from alternative theories of gravity

Allemandi, Gianluca; Francaviglia, M.; Ruggiero, Matteo Luca; Tartaglia, Angelo

doi:10.1007/s10714-005-0195-8

Cited by 128 publications

(119 citation statements)

References 21 publications

(36 reference statements)

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“…It has been argued that higher-curvature theories can arise naturally from string theory under appropriate assumptons [356,357]. Like Einstein gravity, these theories admit a Palatini formulation, which is quite subtle and has been extensive studied [180,[358][359][360][361][362][363][364][365][366][367][368][369][370][371][372]. Models which can cross the phantom divide and have effective equations of state w < −1 have been studied [373][374][375][376], along with investigations into energy conditions in f (R) gravity [377][378][379].…”

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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“…What is less clear in the literature is whether any proposed metric-variation f (R) modification can simultaneously satisfy stringent solar-system bounds on deviations from general relativity as well as accelerate the expansion at late times [63,64,65,66,67,68,69,70,71,72,73,74]. Chiba [75] showed that the fundamental difficulty is that f (R) gravity introduces a scalar degree of freedom with the same coupling to matter as gravity that, at the background cosmological density, is extremely light.…”

Section: Introductionmentioning

confidence: 99%

Models off(R)cosmic acceleration that evade solar system tests

2007

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We study a class of metric-variation f (R) models that accelerates the expansion without a cosmological constant and satisfies both cosmological and solar-system tests in the small-field limit of the parameter space. Solar-system tests alone place only weak bounds on these models, since the additional scalar degree of freedom is locked to the high-curvature general-relativistic prediction across more than 25 orders of magnitude in density, out through the solar corona. This agreement requires that the galactic halo be of sufficient extent to maintain the galaxy at high curvature in the presence of the low-curvature cosmological background. If the galactic halo and local environment in f (R) models do not have substantially deeper potentials than expected in ΛCDM, then cosmological field amplitudes |fR| 10 −6 will cause the galactic interior to evolve to low curvature during the acceleration epoch. Viability of large-deviation models therefore rests on the structure and evolution of the galactic halo, requiring cosmological simulations of f (R) models, and not directly on solar-system tests. Even small deviations that conservatively satisfy both galactic and solar-system constraints can still be tested by future, percent-level measurements of the linear power spectrum, while they remain undetectable to cosmological-distance measures. Although we illustrate these effects in a specific class of models, the requirements on f (R) are phrased in a nearly model-independent manner.

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“…However, this approach was recently criticized [25], since the dynamical equivalence has been used beyond its range of validity. Actually, the debate is still open, and the problem can be faced both in the metric formalism and in the Palatini formalism (see [26,27] and references therein).…”

Section: Introductionmentioning

confidence: 99%

“…In a previous paper [26], one of us studied the consistence of f (R) theories with observational data in the Palatini formalism. We aimed at understanding the corrections to GR arising from specific modifications of the Hilbert-Einstein Lagrangian.…”

Section: Introductionmentioning

confidence: 99%

Solar System planetary orbital motions andf(R) theories of gravity

Ruggiero

Iorio

2007

J. Cosmol. Astropart. Phys.

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In this paper we study the effects of f (R) Theories of Gravity on Solar System gravitational tests. In particular, starting from an exact solution of the field equation in vacuum, in the Palatini formalism, we work out the effects that the modifications to the Newtonian potential would induce on the Keplerian orbital elements of the Solar System planets, and compare them with the latest results in planetary orbit determination from the EPM2004 ephemerides. It turns out that the longitudes of perihelia and the mean longitudes are affected by secular precessions. We obtain the resulting best estimate of the parameter k which, being simply related to the scalar curvature, measures the non linearity of the gravitational theory. We use our results to constrain the cosmological constant and show how f (R) functions can be constrained, in principle. What we obtain suggests that, in agreement with other recent papers, the Solar System experiments are not effective to set such constraints, if compared to the cosmologically relevant values.

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Post-newtonian parameters from alternative theories of gravity

Cited by 128 publications

References 21 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

Models off(R)cosmic acceleration that evade solar system tests

Solar System planetary orbital motions andf(R) theories of gravity

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