# Ellipsoidal potentials¶

class galpy.potential.EllipsoidalPotential.EllipsoidalPotential(amp=1.0, b=1.0, c=1.0, zvec=None, pa=None, glorder=50, ro=None, vo=None, amp_units=None)[source]

Base class for potentials corresponding to density profiles that are stratified on ellipsoids:

$\rho(x,y,z) \equiv \rho(m^2)$

where $$m^2 = x^2+y^2/b^2+z^2/c^2$$. Note that $$b$$ and $$c$$ are defined to be the axis ratios (rather than using $$m^2 = x^2/a^2+y^2/b^2+z^2/c^2$$ as is common).

Implement a specific density distribution with this form by inheriting from this class and defining functions _mdens(self,m) (the density as a function of m), _mdens_deriv(self,m) (the derivative of the density as a function of m), and _psi(self,m), which is:

$\psi(m) = -\int_{m^2}^\infty d m^2 \rho(m^2)$

See PerfectEllipsoidPotential for an example and Merritt & Fridman (1996) for the formalism.

__init__(amp=1.0, b=1.0, c=1.0, zvec=None, pa=None, glorder=50, ro=None, vo=None, amp_units=None)[source]

NAME:

__init__

PURPOSE:

initialize a ellipsoidal potential

INPUT:

amp - amplitude to be applied to the potential (default: 1); can be a Quantity with units that depend on the specific spheroidal potential

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

amp_units - (‘mass’, ‘velocity2’, ‘density’) type of units that amp should have if it has units (passed to Potential.__init__)

ro=, vo= distance and velocity scales for translation into internal units (default from configuration file)

OUTPUT:

(none)

HISTORY:

2018-08-06 - Started - Bovy (UofT)