Double power-law density triaxial potential¶
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class
galpy.potential.
TwoPowerTriaxialPotential
(amp=1.0, a=5.0, alpha=1.5, beta=3.5, b=1.0, c=1.0, zvec=None, pa=None, glorder=50, normalize=False, ro=None, vo=None)¶ Class that implements triaxial potentials that are derived from two-power density models
\[\rho(x,y,z) = \frac{\mathrm{amp}}{4\,\pi\,a^3}\,\frac{1}{(m/a)^\alpha\,(1+m/a)^{\beta-\alpha}}\]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=5.0, alpha=1.5, beta=3.5, b=1.0, c=1.0, zvec=None, pa=None, glorder=50, normalize=False, ro=None, vo=None)¶ NAME:
__init__PURPOSE:
initialize a triaxial two-power-density 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)
alpha - inner power (0 <= alpha < 3)
beta - outer power ( beta > 2)
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 (rad or Quantity)
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.
ro=, vo= distance and velocity scales for translation into internal units (default from configuration file)
OUTPUT:
(none)HISTORY:
2016-05-30 - Started - Bovy (UofT)
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