0 Assigned ID: 1093 ----- Attempting Submission 1 (Fri Apr 10 23:52:21 GMT 2015) ----- We propose to investigate a newly discovered feature in the density profiles of dark matter halos found in numerical simulations. This feature, a localized steepening of the density profile associated with backsplash material, could provide a calibratable standard ruler enabling new probes of the background cosmology. The proposed theoretical work would directly benefit HST observing programs that measure weak gravitational lensing of galaxy clusters, by providing a new cosmological test that cluster observations could perform, possibly using existing data. COSMOLOGY 0 Regular false false false false true SUPPORTED