Observing dynamical friction in galaxy clusters
  We present a novel method to detect the effects of dynamical friction in
observed galaxy clusters. Following accretion into clusters, massive satellite
galaxies will backsplash to systematically smaller radii than less massive
satellites, an effect that may be detected by stacking the number density
profiles of galaxies around clusters. We show that this effect may be
understood using a simple toy model which reproduces the trends with halo
properties observed in simulations. We search for this effect using SDSS
redMaPPer clusters with richness 10<lambda<20, and find that bright (M_i<-21.5)
satellites have smaller splashback radii than fainter (M_i>-20) satellites at
99% confidence.
