Revisiting the screening mechanism in f(R) gravity.

We reexamine the screening mechanism in f(R) gravity using N-body simulations. By explicitly examining the relation between the extrascalar field δfR and the gravitational potential ϕ in the perturbed Universe, we find that the relation between these two fields plays an important role in understanding the screening mechanism. We show that the screening mechanism in f(R) gravity depends mainly on the depth of the potential well and find a useful condition for identifying unscreened haloes in simulations. We also discuss the potential application of our results to real galaxy surveys