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Advances in Astronomy
Volume 2011, Article ID 903429, 8 pages
Research Article

Dark Matter Halos: The Dynamical Basis of Effective Empirical Models

1Department of Physics, University of Rome ‘Tor Vergata’, Via della Ricerca Scientifica 1, 00133 Rome, Italy
2Astrophysics Sector, SISSA/ISAS, Via Bonomea 265, 34136 Trieste, Italy

Received 27 May 2010; Accepted 31 August 2010

Academic Editor: Alberto J. Castro-Tirado

Copyright © 2011 Andrea Lapi and Alfonso Cavaliere. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We investigate the dynamical basis of the classic empirical models (specifically, Sérsic-Einasto and generalized NFW) that are widely used to describe the distributions of collisionless matter in galaxies. We submit that such a basis is provided by our -profiles, shown to constitute solutions of the Jeans dynamical equilibrium with physical boundary conditions. We show how to set the parameters of the empirical in terms of the dynamical models; we find the empirical models, and specifically Sérsic-Einasto, to constitute a simple and close approximation to the dynamical models. Finally, we discuss how these provide a useful baseline for assessing the impact of the small-scale dynamics that may modulate the density slope in the central galaxy regions.