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 extra scalar field $\delta f_R$ and the gravitational potential $\phi$ 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 halos in simulations. We also discuss the potential application of our results to real galaxy surveys. 
Jian-hua He (INAF-Milan), Baojiu Li (ICC, Durham), Adam J. Hawken   (INAF-Milan), Benjamin R. Granett (INAF-Milan)
astro-ph.CO