Effective Dark Matter Halo catalog in $f(R)$ gravity

We introduce the idea of {\it effective} dark matter halo catalog in $f(R)$ gravity, which is built using the {\it effective} density field. Using a suite of high resolution N-body simulations, we find that the dynamical properties of halos, such as the distribution of density, velocity dispersion, specific angular momentum and spin, in the effective catalog of $f(R)$ gravity closely mimic those in the $\Lambda$CDM model. Thus, when using effective halos, an $f(R)$ model can be viewed as a $\Lambda$CDM model. This effective catalog therefore provides a convenient way for studying the baryonic physics, the galaxy halo occupation distribution and even semi-analytical galaxy formation in $f(R)$ cosmologies.