Scaling solutions in general nonminimal coupling theories

Amendola, Luca

doi:10.1103/physrevd.60.043501

Cited by 586 publications

(607 citation statements)

References 23 publications

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“…For a minimally coupled field, the possible scaling behaviors and the corresponding potentials can be classified [12]. As for a non-minimally coupled field, a subclass of theories was considered in [45], for which…”

Section: Scaling Solutionsmentioning

confidence: 99%

Scalar-tensor gravity in an accelerating universe

2001

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We consider scalar-tensor theories of gravity in an accelerating universe. The equations for the background evolution and the perturbations are given in full generality for any parametrization of the Lagrangian, and we stress that apparent singularities are sometimes artifacts of a pathological choice of variables. Adopting a phenomenological viewpoint, i.e., from the observations back to the theory, we show that the knowledge of the luminosity distance as a function of redshift up to z ∼ (1 − 2), which is expected in the near future, severely constrains the viable subclasses of scalar-tensor theories. This is due to the requirement of positive energy for both the graviton and the scalar partner. Assuming a particular form for the Hubble diagram, consistent with present experimental data, we reconstruct the microscopic Lagrangian for various scalar-tensor models, and find that the most natural ones are obtained if the universe is (marginally) closed.

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Section: Scaling Solutionsmentioning

confidence: 99%

Scalar-tensor gravity in an accelerating universe

2001

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“…(10). When α ¼ 0, the perturbation equations (15) and (16) reduce to the equations used in Ref. [33].…”

Section: Simulation Detailsmentioning

confidence: 99%

“…where κ 2 ¼ 8πG with G being Newton's constant, g is the determinant of the metric g μν , L ðmÞ is the Lagrangian density for matter, and fðRÞ is an arbitrary function of the Ricci scalar curvature R [5][6][7][8][9][10][11][12][13][14][15][16] (see Refs. [22,23] for reviews).…”

Section: F ðRþ Modelmentioning

confidence: 99%

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Revisiting the screening mechanism inf(R)gravity

Hawken

et al. 2014

Phys. Rev. D

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We reexamine the screening mechanism in fðRÞ gravity using N-body simulations. By explicitly examining the relation between the extrascalar field δf R and the gravitational potential ϕ in the perturbed Universe, we find that the relation between these two fields plays an important role in understanding the screening mechanism. We show that the screening mechanism in fðRÞ gravity depends mainly on the depth of the potential well and find a useful condition for identifying unscreened haloes in simulations. We also discuss the potential application of our results to real galaxy surveys.

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“…however, is also widely considered in the literature (see, e.g., Ellis et al (1989);Wetterich (1995); Amendola (1999); Amendola & Tocchini-Valentini (2002); Macciò et al (2004); Baldi et al (2010)), together with other possible options for energy transfer between DM and DE (see, e.g., Lopez Honorez et al (2010)). The coupling…”

Section: Coupled Dark Energy In the Early Universementioning

confidence: 99%

Strongly coupled dark energy cosmologies: preservingΛCDM success and easing low scale problems – I. Linear theory revisited

Bonometto¹,

Mainini

Macciò

2015

Mon. Not. R. Astron. Soc.

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In this first paper we discuss the linear theory and the background evolution of a new class of models we dub SCDEW: Strongly Coupled DE, plus WDM. In these models, WDM dominates today's matter density; like baryons, WDM is uncoupled. Dark Energy is a scalar field Φ; its coupling to ancillary CDM, whose today's density is ≪ 1 %, is an essential model feature. Such coupling, in fact, allows the formation of cosmic structures, in spite of very low WDM particle masses (∼ 100 eV). SCDEW models yields Cosmic Microwave Background and linear Large Scale features substantially undistinguishable from ΛCDM, but thanks to the very low WDM masses they strongly alleviate ΛCDM issues on small scales, as confirmed via numerical simulations in the II associated paper. Moreover SCDEW cosmologies significantly ease the coincidence and fine tuning problems of ΛCDM and, by using a field theory approach, we also outline possible links with inflationary models. We also discuss a possible fading of the coupling at low redshifts which prevents non linearities on the CDM component to cause computational problems. The (possible) low-z coupling suppression, its mechanism, and its consequences are however still open questions -not necessarily problems-for SCDEW models. The coupling intensity and the WDM particle mass, although being extra parameters in respect to ΛCDM , are found to be substantially constrained a priori so that, if SCDEW is the underlying cosmology, we expect most data to fit also ΛCDM predictions.

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Scaling solutions in general nonminimal coupling theories

Cited by 586 publications

References 23 publications

Scalar-tensor gravity in an accelerating universe

Scalar-tensor gravity in an accelerating universe

Revisiting the screening mechanism inf(R)gravity

Strongly coupled dark energy cosmologies: preservingΛCDM success and easing low scale problems – I. Linear theory revisited

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