Phantom crossing, equation-of-state singularities, and local gravity constraints in f(R) models

By Luca Amendola, S. Tsujikawa. 2007

244 citations recorded by the source corpus.

Abstract We identify the class of f ( R ) dark energy models which have a viable cosmology, i.e. a matter dominated epoch followed by a late-time acceleration. The deviation from a ΛCDM model ( f = R − Λ ) is quantified by the function m = R f , R R / f , R . The matter epoch corresponds to m ( r = − 1 ) ≃ + 0 (where r = − R f , R / f ) while the accelerated attractor exists in the region 0 ⩽ m 1 . We find that the equation of state w DE of all such “viable” f ( R ) models exhibits two features: w DE diverges at some redshift z c and crosses the cosmological constant boundary (“phantom crossing”) at a redshift z b smaller than z c . Using the observational data of Supernova Ia and Cosmic Microwave Background, we obtain the constraint m O ( 0.1 ) and we find that the phantom crossing could occur at z b ≳ 1 , i.e., within reach of observations. If we add local gravity constraints, the bound on m becomes very stringent, with m several orders of magnitude smaller than unity in the region whose density is much larger than the present cosmological density. The representative models that satisfy both cosmological and local gravity constraints take the asymptotic form m ( r ) = C ( − r − 1 ) p with p > 1 as r approaches −1.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7ed41b5a27e4f81d396f9d076398565c71ef6fd8

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f(R) Theories Of Gravity (2008, background): “On the negative side, these theories are observationally indistinguishable from a cosmological constant and they have been dubbed “vanilla f(R) gravity” (Amendola et al., 2007a,b,c; Amendola and Tsujikawa, 2008; Faulkner et al., 2007).”