Imprint of f(R) gravity on nonlinear structure formation

We test the imprint of f(R) modified gravity on the halo mass function, using N-body simulations and a theoretical model developed in [M. Kopp, Phys. Rev. D 88, 084015 (2013)]. We find a good agreement between theory and simulations ∼5%. We extend the theoretical model to the conditional mass function and apply it to the prediction of the linear halo bias in f(R) gravity. Using the halo model we obtain a prediction for the nonlinear matter power spectrum accurate to ∼10% at z=0 and up to k=2h/Mpc. We also study halo profiles for the f(R) models and find a deviation from the standard general relativity (GR) result up to 40%, depending on the halo masses and redshift. This has not been pointed out in previous analysis. Finally we study the number density and profiles of voids identified in these f(R) N-body simulations. We underline the effect of the bias and the sampling to identify voids. We find significant deviation from GR when measuring the f(R) void profiles with fR0<-10-6.