Cluster density profiles as a test of modified gravity

We present a new test of gravitational interactions at the r (0. 2--20) Mpc scale, around the virial radius of dark matter halos measured through cluster-galaxy lensing of maxBCG clusters from the Sloan Digital Sky Survey (SDSS). We employ predictions from self-consistent simulations of f (R) gravity to find an upper bound on the background field amplitude of |fₑ₀|<3. 510^-3 at the 1D-marginalized 95% confidence level. As a model-independent assessment of the constraining power of cluster profiles measured through weak gravitational lensing, we also constrain the amplitude F₀ of a phenomenological modification based on the profile enhancement induced by f (R) gravity when not including effects from the increased cluster abundance in f (R). In both scenarios, dark-matter-only simulations of the concordance model corresponding to |fₑ₀|=0 and F₀=0 are consistent with the lensing measurements, i. e. , at the 68% and 95% confidence level, respectively.