Cosmology of modified Gauss-Bonnet gravity

By Baojiu Li, John D. Barrow, D. Mota. 2007

241 citations recorded by the source corpus.

We consider the cosmology where some function f(G) of the Gauss-Bonnet term G is added to the gravitational action to account for the late-time accelerating expansion of the universe. The covariant and gauge invariant perturbation equations are derived with a method which could also be applied to general f(R,R{sup ab}R{sub ab},R{sup abcd}R{sub abcd}) gravitational theories. It is pointed out that, despite their fourth-order character, such f(G) gravity models generally cannot reproduce arbitrary background cosmic evolutions; for example, the standard {lambda}CDM paradigm with {omega}{sub DE}=0.76 cannot be realized in f(G) gravity theories unless f is a true cosmological constant because it imposes exclusionary constraints on the form of f(G). We analyze the perturbation equations and find that, as in the f(R) model, the stability of early-time perturbation growth puts some constraints on the functional form of f(G), in this case {partial_derivative}{sup 2}f/{partial_derivative}G{sup 2}<0. Furthermore, the stability of small-scale perturbations also requires that f not deviate significantly from a constant. These analyses are illustrated by numerically propagating the perturbation equations with a specific model reproducing a representative {lambda}CDM cosmic history. Our results show how the f(G) models are highly constrained by cosmological data.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/b3966ee2ee538e24a1258da6282193f9035f40a9

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Citations in the corpus

Modified Gravity and Cosmology (2011, methodology): “For theories with L = f(R,G) it can be seen that m−2 0 = 1 3R (2)fGG, so that the condition m 2 0 > 0 is equivalent to the stability condition fGG > 0 found in [371, 370] and [791] in the context of cosmology.”
f(R) Theories (2010, background): “The cosmological dynamics in f(G) dark energy models have been discussed in [458, 165, 383, 188, 633, 430].”