Construction of cosmologically viable f(G) dark energy models

By Antonio de Felice, S. Tsujikawa. 2008

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We derive conditions under which f(G) gravity models, whose Lagrangian densities f are written in terms of a Gauss-Bonnet term G, are cosmologically viable. The most crucial condition to be satisfied is that f_GG, the second derivative of f with respect to G, must be positive, which is required to ensure the stability of a late-time de-Sitter solution as well as the existence of standard radiation/matter dominated epochs. We present a number of explicit f(G) models in which a cosmic acceleration is followed by the matter era. We find that the equation of state of dark energy can cross the phantom divide before reaching the present Universe. The viable models have asymptotic behavior f_GG goes to +0 when |G| goes to infinity, in which case a rapid oscillation of perturbations occurs unless such an oscillating degree of freedom is suppressed relative to a homogeneous mode in the early universe. We also introduce an iterative method to avoid numerical instabilities associated with a large mass of the oscillating mode. Comment: 12 pages, 5 figures, uses ReVTeX. Added references, minor corrections

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2d696043f42e3c69fc9ea8b26660062b0f223b59

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Citations in the corpus

New observational constraints on f(R) gravity from cosmic chronometers (2016, background): “However, one can construct many other classes of curvature-based modified gravities, such as f(G) gravity [27, 28], Lovelock gravity [29, 30], Weyl gravity [31, 32], Galileon theory [33–36], or even extend to torsion-based modifications, such as f(T ) gravity [37–42], f(T, TG) gravity [43–45], etc.”