Triaxial NFW potential¶
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class
galpy.potential.
TriaxialNFWPotential
(amp=1.0, a=2.0, b=1.0, c=1.0, zvec=None, pa=None, normalize=False, conc=None, mvir=None, glorder=50, vo=None, ro=None, H=70.0, Om=0.3, overdens=200.0, wrtcrit=False)[source]¶ Class that implements the triaxial NFW potential
\[\rho(x,y,z) = \frac{\mathrm{amp}}{4\,\pi\,a^3}\,\frac{1}{(m/a)\,(1+m/a)^{2}}\]with
\[m^2 = x'^2 + \frac{y'^2}{b^2}+\frac{z'^2}{c^2}\]and \((x',y',z')\) is a rotated frame wrt \((x,y,z)\) specified by parameters
zvec
andpa
which specify (a)zvec
: the location of the \(z'\) axis in the \((x,y,z)\) frame and (b)pa
: the position angle of the \(x'\) axis wrt the \(\tilde{x}\) axis, that is, the \(x\) axis after rotating tozvec
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__init__
(amp=1.0, a=2.0, b=1.0, c=1.0, zvec=None, pa=None, normalize=False, conc=None, mvir=None, glorder=50, vo=None, ro=None, H=70.0, Om=0.3, overdens=200.0, wrtcrit=False)[source]¶ NAME:
__init__PURPOSE:
Initialize a triaxial NFW potentialINPUT:
amp - amplitude to be applied to the potential (default: 1); can be a Quantity with units of mass or Gxmass
a - scale radius (can be Quantity)
b - y-to-x axis ratio of the density
c - z-to-x axis ratio of the density
zvec= (None) If set, a unit vector that corresponds to the z axis
pa= (None) If set, the position angle of the x axis
glorder= (50) if set, compute the relevant force and potential integrals with Gaussian quadrature of this order
normalize - if True, normalize such that vc(1.,0.)=1., or, if given as a number, such that the force is this fraction of the force necessary to make vc(1.,0.)=1.
Alternatively, NFW potentials can be initialized using
conc= concentration
mvir= virial mass in 10^12 Msolar
in which case you also need to supply the following keywords
H= (default: 70) Hubble constant in km/s/Mpc
Om= (default: 0.3) Omega matter
overdens= (200) overdensity which defines the virial radius
wrtcrit= (False) if True, the overdensity is wrt the critical density rather than the mean matter density
ro=, vo= distance and velocity scales for translation into internal units (default from configuration file)
OUTPUT:
(none)HISTORY:
2016-05-30 - Written - Bovy (UofT)
2018-08-06 - Re-written using the general EllipsoidalPotential class - Bovy (UofT)
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