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Navarro-Frenk-White profile : ウィキペディア英語版
Navarro–Frenk–White profile
The Navarro–Frenk–White (NFW) profile is a spatial mass distribution of dark matter fitted to dark matter haloes 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.
==Density distribution==

In the NFW profile, the density of dark matter as a function of radius is given by:
:
\rho (r)=\frac\left(1~+~\frac\right)^2}

where ''ρ''0 and the "scale radius", ''Rs'', are parameters which vary from halo to halo.
The integrated mass inside of some radius ''R''max is
:
M=\int_0^ 4\pi r^2 \rho (r) \, dr=4\pi \rho_0 R_s^3 \left()

The total mass is divergent, but it is often useful to take the edge of the halo to be the virial radius, ''R''vir, which is related to the "concentration parameter", ''c'', and scale radius via
:
R_\mathrm=cR_s

The virial radius is often referred to as R_ , and is defined as the radius at which the average density within this radius is 200 times the critical density. In this case, the total mass in the halo is
:
M=\int_0^\right )

The value of ''c'' is roughly 10 or 15 for the Milky Way, and may range from 4 to 40
for halos of various sizes.
The integral of the ''squared density'' is
:
\int_0^ 4\pi r^2 \rho (r)^2 \, dr=\frac R_s^3 \rho_0^2
\left()

so that the mean squared density inside of ''R''max is
:
\langle \rho^2 \rangle_=\frac
\left()

which for the virial radius simplifies to
:
\langle \rho^2 \rangle_
\left()
\approx \frac

and the mean squared density inside the scale radius is simply
:
\langle \rho^2 \rangle_=\frac\rho_0^2


抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)
ウィキペディアで「Navarro–Frenk–White profile」の詳細全文を読む



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