Navarro–Frenk–White profile

The Navarro–Frenk–White (NFW) profile is a spatial mass distribution of dark matter fitted to dark matter halos identified in N-body simulations by Julio Navarro, Carlos Frenk and Simon White. The NFW profile is one of the most commonly used model profiles for dark matter halos. The substantial impact of NFW's work on theoretical understanding of cosmic structure formation can be traced to three key insights.

1) In cosmological models where dark matter structure grows hierarchically from weak initial fluctuations, dark matter halos are almost self-similar; halo regions which are close to dynamical equilibrium are adequately represented for all masses and at all times by a simple analytic formula with only two free parameters, a characteristic density and a characteristic size.

2) These two parameters are related with rather little scatter; larger halos are less dense. The size-density relation depends on cosmological parameters and so can be used to constrain these observationally.

3) The characteristic density of a halo is linked to the mean density of the universe at its epoch of maximal growth. Thus the size-density relation reflects the fact that larger halos typically assembled at later times.