Observational bounds on modified gravity models

January 2008 • 2008PhRvD..77b4017D

Authors • de Felice, Antonio • Mukherjee, Pia • Wang, Yun

Abstract • Modified gravity provides a possible explanation for the currently observed cosmic acceleration. 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 modified gravity models quite dramatically.

Links

• PREPRINT http://arxiv.org/abs/0706.1197
• ELECTR http://link.aps.org/doi/10.1103/PhysRevD.77.024017
• SPIRES http://inspirehep.net/search?p=find+eprint+arXiv:0706.1197