Properties of spherical galaxies and clusters with an NFW density profile
Abstract
Using the standard dynamical theory of spherical systems, we calculate the properties of spherical galaxies and clusters whose density profiles obey the universal form first obtained in highresolution cosmological Nbody simulations by Navarro, Frenk & White (NFW). We adopt three models for the internal kinematics: isotropic velocities, constant anisotropy and increasingly radial OsipkovMerritt anisotropy. Analytical solutions are found for the radial dependence of the mass, gravitational potential, velocity dispersion, energy and virial ratio and we test their variability with the concentration parameter describing the density profile and amount of velocity anisotropy. We also compute structural parameters, such as halfmass radius, effective radius and various measures of concentration. Finally, we derive projected quantities, the surface mass density and lineofsight as well as aperturevelocity dispersion, all of which can be directly applied in observational tests of current scenarios of structure formation. On the mass scales of galaxies, if constant masstolight is assumed, the NFW surface density profile is found to fit HubbleReynolds laws well. It is also well fitted by Sérsic R^{1/m} laws, for m~=3, but in a much narrower range of m and with much larger effective radii than are observed. Assuming in turn reasonable values of the effective radius, the mass density profiles imply a masstolight ratio that increases outwards at all radii.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 February 2001
 DOI:
 10.1046/j.13658711.2001.04007.x
 arXiv:
 arXiv:astroph/0002395
 Bibcode:
 2001MNRAS.321..155L
 Keywords:

 METHODS: ANALYTICAL;
 GALAXIES: CLUSTERS: GENERAL;
 LARGESCALE STRUCTURE OF UNIVERSE;
 methods: analytical;
 galaxies: clusters: general;
 largescale structure of Universe;
 Astrophysics
 EPrint:
 13 pages, 13 figures, uses mn.sty and epsf.tex, revised version accepted by MNRAS (results for anisotropic models added, comparison with observations extended)