Scale-dependent growth of structures in viable f(R) theories

Abstract

f(R) theories are an alternative approach at the phenomenon of cosmic acceleration, in which the Einstein-Hilbert action for gravity is modified by adding a function of the Ricci scalar, f(R). While at the background level viable f(R) models must closely mimic LCDM, the difference in their prediction for the growth of large scale structures can be sufficiently large to leave detectable signatures in future surveys. In this talk, after reviewing the conditions for the background viability of f(R) theories, I will focus on scalar perturbations. I will present in some details the dynamics of linear perturbations, showing what are the characteristic imprints of f(R) models in the growth of structures and consider possible observational tests