Observational Bounds on Modified Gravity Models

Abstract

Modified gravity provides a possible explanation for the currently observed cosmic accelaration. In this paper, we study general classes of modified gravity models. The Einstein-Hilbert action is modified by using general functions of the Ricci and the Gauss-Bonnet scalars, both in the metric and in the Palatini formalisms. We do not use an explicit form for the functions, but a general form with a valid Taylor expansion up to second order about redshift zero in the Riemann-scalars. The coefficients of this expansion are then reconstructed via the cosmic expansion history measured using current cosmological observations. These are the quantities of interest for theoretical considerations relating to ghosts and instabilities. We find that current data provide interesting constraints on the coefficients. The next-generation dark energy surveys should shrink the allowed parameter space for modifed gravity models quite dramatically.

23 pages, 5 figures, uses RevTeX

References in corpus (6)

• Models of f(R) Cosmic Acceleration that Evade Solar-System Tests
• Constraining f(R) Gravity as a Scalar Tensor Theory
• The Cosmology of Modified Gauss-Bonnet Gravity
• Stability of Cosmological Solution in f(R) Models of Gravity
• f(R) gravity theories in Palatini formalism: cosmological dynamics and observational constraints
• Ghost Constraints on Modified Gravity

Cited by in corpus (5)

• Figure of Merit for Dark Energy Constraints from Current Observational Data
• Density perturbations in f(R) gravity theories in metric and Palatini formalisms
• Planck priors for dark energy surveys
• Aspects of Infrared Modifications of Gravity
• Multicomponent solution in modified theory of gravity in the early universe