We explore similarities in the luminosity distribution of early type galaxies and the mass profiles of LCDM halos. The spatial structure of these systems may be accurately described by a simple law where the logarithmic slope of the projected density is a power law of radius; the Sérsic law. We show that this law provides a significantly better fit than a three-parameter generalization of the NFW profile and derive the best-fitting Sérsic parameters for a set of high-resolution LCDM halos spanning a wide range in mass. The mean Sérsic n values are 3.0 for dwarf- and galaxy-sized halos and 2.4 for cluster-sized halos, similar to the values that characterize luminous elliptical galaxies. We discuss possible reasons why the same law should describe dark and luminous systems that span a range of over seven decades in mass.

Publication Date



This is the pre-print of an article published by the American Astronomical Society. The final, published version is available here: https://doi.org/10.1086/430636

© 2005 The American Astronomical Society

Also archived in: arXiv: astro-ph/0502515 v1 24 Feb 2005

DM was supported by grants AST-0206031, AST-0420920 and AST-0437519 from the NSF and grantNNG04GJ48G fromNASA. JFN acknowledges support fromthe Alexander von Humboldt Foundation.

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus