Navarro-Frenk-White profile

The Navarro-Frenk-White profile or NFW profile is a spatial distribution of dark matter predicted from N-body simulations by Julio Navarro, Carlos Frenk and Simon White.cite journal|author = Navarro, Julio F.; Frenk, Carlos S.; White, Simon D. M.|title = The Structure of Cold Dark Matter Halos|journal = The Astrophysical Journal|volume = 463|pages = 563|date = May 10 1996|url = http://adsabs.harvard.edu/abs/1996ApJ...462..563N|doi = 10.1086/177173] The NFW profile is one of the most commonly used model profiles for dark matter halos.cite journal|author = Bertone, Gianfranco; Hooper, Dan; Silk, Joseph|title = Particle dark matter: evidence, candidates and constraints|date = January 2005|journal = Physics Reports|volume = 405|issue = 5-6|pages = 279–390|url = http://adsabs.harvard.edu/abs/2005PhR...405..279B|doi = 10.1016/j.physrep.2004.08.031]

Density distribution

In the profile, the density of dark matter in space is given by:

$ho\; (r)\; =\; frac\{\; ho\_0\}\{frac\{r\}\{R\}left(1~+~frac\{r\}\{R\}\; ight)^2\}$

Both ρ₀ and "R" are parameters which vary from halo to halo.

Dark Matter Simulations

The NFW profile is an approximation to the equilibrium configuration of dark matter produced in simulations of collisionless dark matter particles by numerous groups of scientists. [cite journal|author = Y. P. Jing|title = The Density Profile of Equilibrium and Nonequilibrium Dark Matter Halos|journal = The Astrophysical Journal|date = 20 May 2000|volume = 535|issue = 1|pages = 30–36|url = http://adsabs.harvard.edu/cgi-bin/bib_query?2000ApJ...535...30J|doi = 10.1086/308809] Before the dark matter virializes, the distribution of dark matter deviates from an NFW profile, and significant substructure is observed in simulations both during and after the collapse of the halos. Alternative models, for instance the Einasto profile, have been shown to represent the dark matter profiles of simulated halos as well as or better than the NFW profile. [cite journal|author = D. Merritt, A. Graham, B. Moore, J. Diemand, B. Terzić|title = Empirical Models for Dark Matter Halos|journal = The Astronomical Journal|date = 20 December 2006|volume = 132|issue = 6|pages = 2685–2700|url = http://adsabs.harvard.edu/abs/2006AJ....132.2685M|doi = 10.1086/508988] .

Observations of Halos

The observations of both the Milky Way and M31 may be compatible with the NFW profile for the dark matter halo.cite journal|author = Klypin, Anatoly; Zhao, HongSheng; Somerville, Rachel S.|title = ΛCDM-based Models for the Milky Way and M31. I. Dynamical Models|date = 10 July 2002|journal = The Astrophysical Journal|volume = 573|issue = 2|pages = 597–613|url = http://adsabs.harvard.edu/abs/2002ApJ...573..597K|doi = 10.1086/340656]

References