Constraining Inverse Curvature Gravity with Supernovae

TL;DR

It is shown that models of generalized modified gravity, with inverse powers of the curvature, can explain the current accelerated expansion of the Universe without resorting to dark energy and without conflicting with solar system experiments.

Abstract

We show that the current accelerated expansion of the Universe can be explained without resorting to dark energy. Models of generalized modified gravity, with inverse powers of the curvature can have late time accelerating attractors without conflicting with solar system experiments. We have solved the Friedman equations for the full dynamical range of the evolution of the Universe. This allows us to perform a detailed analysis of Supernovae data in the context of such models that results in an excellent fit. Hence, inverse curvature gravity models represent an example of phenomenologically viable models in which the current acceleration of the Universe is driven by curvature instead of dark energy. If we further include constraints on the current expansion rate of the Universe from the Hubble Space Telescope and on the age of the Universe from globular clusters, we obtain that the matter content of the Universe is 0.07 <= omega_m <= 0.21 (95% Confidence). Hence the inverse curvature gravity models considered can not explain the dynamics of the Universe just with a baryonic matter component.

Figures (2)

• Figure 1: 1 and 2-$\sigma$ joint likelihoods on ${\bar{\omega}}_m$ and $\alpha$. In the low region $\sigma=-1$ whereas in the high region $\sigma=+1$. The shaded area on the right determines the region $\alpha>\alpha_4$ that is excluded because of a singularity being hit in the past. The diamonds denote the maximum likelihood points.
• Figure 2: The 1- and 2-$\sigma$ joint likelihoods in the $\omega_{\rm m}-\hat{\mu}$ plane, when additional priors on $H_0$ and the age of the Universe are imposed. On the left for the low region and on the right for the high region. Diamonds are the maximum likelihoods. Further, the dashed contours are the joint likelihoods if we impose only the $H_0$ prior.