Growth index of DGP model and current growth rate data

Abstract

Recently, some efforts focus on differentiating dark energy and modified gravity with the growth function δ(z). In the literature, it is useful to parameterize the growth rate f ≡ d ln δ/d ln a = Ω γ m with the growth index γ. In this note, we consider the general DGP model with any Ω k . We confront the growth index of DGP model with currently available growth rate data and find that the DGP model is still consistent with it. This implies that more and better growth rate data are required to distinguish between dark energy and modified gravity.

Growth factor parametrization and modified gravity

“…[27,28]. Recently, the use of the growth rate of matter perturbation in addition to the expansion history of the Universe to differentiate dark energy models and modified gravity attracted much attention [29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44].…”

Linear growth in power lawf(T)gravity

“…Specifically, the idea of utilizing the so-called growth index, γ (first introduced by [16]), of linear matter perturbations as a gravity tool is not new and indeed there is a lot of work in the literature. There are plenty of studies available in which one can find the theoretical form of the growth index for various cosmological models, including scalar field DE [17][18][19][20][21][22], DGP [21,[23][24][25], Finsler-Randers [26] and f (R) [27,28].…”

Precision growth index using the clustering of cosmic structures and growth data

“…In the case of the concordance ΛCDM model (w(z) = −1) the above formula reduces to γ ≈ 6/11. Considering the braneworld model of [18] we have γ ≈ 11/16 (see [12,19,20,21]). Finally, for some f (R) gravity models it has been found that γ ≃ 0.415 − 0.21z for various parameter values (see [22,23]), while for the Finsler-Randers cosmology, Basilakos & Stavrinos [24] found γ ≈ 9/14.…”