Real- and redshift-space halo clustering in ƒ(R) cosmologies

We present two-point correlation function statistics of the mass and the halos in the chameleon ƒ(R) modified gravity scenario using a series of large volume N-body simulations. Three distinct variations of ƒ(R) are considered (F4, F5 and F6) and compared to a fiducial ΛCDM model in the redshift range z∈[0,1]. We find that the matter clustering is indistinguishable for all models except for F4, which shows a significantly steeper slope. The ratio of the redshift- to real-space correlation function at scales >20h⁻¹Mpc agrees with the linear General Relativity (GR) Kaiser formula for the viable ƒ(R) models considered. We consider three halo populations characterized by spatial abundances comparable to that of luminous red galaxies (LRGs) and galaxy clusters. The redshift-space halo correlation functions of F4 and F5 deviate significantly from ΛCDM at intermediate and high redshift, as the ƒ(R) halo bias is smaller or equal to that of the ΛCDM case. Finally we introduce a new model independent clustering statistic to distinguish ƒ(R) from GR: the relative halo clustering ratio - R. The sampling required to adequately reduce the scatter in R will be available with the advent of the next generation galaxy redshift surveys. This will foster a prospective avenue to obtain largely model-independent cosmological constraints on this class of modified gravity models.