Solar System tests and chameleon effect in f (R) gravity

Abstract

Using a novel and self-consistent approach that avoids the scalar-tensor identification in the Einstein frame, we reanalyze the viability of f(R) gravity within the context of solar-system tests. In order to do so, we depart from a simple but fully relativistic system of differential equations that describe a compact object in a static and spherically symmetric spacetime, and then we make suitable linearizations that apply to nonrelativistic objects such as the Sun. We then show clearly under which conditions the emerging chameleonlike mechanism can lead to a post-Newtonian parameter γ compatible with the observational bounds. To illustrate this method, we use several specific f(R) models proposed to explain the current acceleration of the Universe, and we show which of them are able to satisfy those bounds.