Talk abstract details

A complete description of density, vorticity and gravitational wave perturbations of FRW models in f(R) gravity is presented using the 1+3 covariant and gauge-invariant approach of Ellis and Bruni. A complete set of perturbation equations are given together with a procedure for mapping the physical variables to the standard metric approach to perturbations.

We apply our results to R^n gravity and compare the evolution of perturbations with what is obtained in General Relativity, giving the range of values of n, for which R^n gravity is consistent with structure formation, and type 1a supernovae measurements.