Scalar-tensor gravity in an accelerating universe

By G. Esposito-Farèse, D. Polarski. 2000

337 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/f330ee2e5575979dec3bbf2ef84cdbc3a21833c3

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Citations in the corpus

Varying Constants, Gravitation and Cosmology (2010, neutral): “, [191]) by (︂ dφ* dφ )︂2 = 3 4 (︂ d lnF (φ) dφ )︂2 + 1 2F (φ) , A(φ*) = F −1/2(φ), 2V (φ*) = U(φ)F −2(φ),”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “We include scalar–tensor theories among ‘interacting cosmologies’ because, via a Weyl transformation, they are equivalent to a GR framework (minimal coupling to gravity) in which the dark-energy scalar field φ is coupled (universally) to all species (Wetterich 1988; Maeda 1989; Wands 1994; Esposito-”
Tension and constraints on modified gravity parametrizations of $G_{\textrm{eff}}(z)$ from growth rate and Planck data (2017, methodology): “However, as also noted in Ref.”
f(R) Theories (2010, background): “In scalar-tensor dark energy models, for example, it is known that a singular behavior sometimes arises at low-redshifts in such a procedure [234, 271].”