A universal density profile for dark and luminous matter?

We explore similarities in the luminosity distribution of early-type galaxies and the mass profiles of Lambda CDM halos. The spatial structure of these systems may be accurately described by a simple law in which the logarithmic slope of the density varies as a power of the radius: the Sersic law. We show that this law provides a significantly better fit to a set of high-resolution Lambda CDM halos than a three-parameter generalization of the Navarro-Frenk-White profile. We discuss possible reasons why the same law should describe dark and luminous systems that span a range of over 7 decades in mass.