Arbitrary constant-anisotropy DF

class galpy.df.constantbetadf(pot=None, denspot=None, beta=0.0, twobeta=None, rmax=None, rmin=None, scale=None, ro=None, vo=None)[source]

Class that implements DFs of the form \(f(E,L) = L^{-2\beta} f_1(E)\) with constant \(\beta\) anisotropy parameter for a given density profile

__init__(pot=None, denspot=None, beta=0.0, twobeta=None, rmax=None, rmin=None, scale=None, ro=None, vo=None)[source]

Initialize a spherical DF with constant anisotropy parameter

Parameters:

  • pot (Potential instance or a combined potential formed using addition (pot1+pot2+…), optional) – Potential instance or a combined potential formed using addition (pot1+pot2+…)

  • denspot (Potential instance or a combined potential formed using addition (pot1+pot2+…), optional) – Potential instance or a combined potential formed using addition (pot1+pot2+…) that represent the density of the tracers (assumed to be spherical; if None, set equal to pot)

  • beta (float, optional) – anisotropy parameter

  • twobeta (float, optional) – twice the anisotropy parameter (useful for eta = half-integer, which is a special case); has priority over beta

  • rmax (float or Quantity, optional) – maximum radius to consider; DF is cut off at E = Phi(rmax)

  • rmin (float or Quantity, optional) – Minimum radius to consider; the distribution function is cut off at E = Phi(rmin). For potentials that diverge at r=0 (e.g., PowerSphericalPotential with alpha > 2), this is automatically set to a small value if not specified.

  • scale (float or Quantity, optional) – Characteristic scale radius to aid sampling calculations. Optional and will also be overridden by value from pot if available.

  • ro (float or Quantity, optional) – Distance scale for translation into internal units (default from configuration file).

  • vo (float or Quantity, optional) – Velocity scale for translation into internal units (default from configuration file).

Notes

  • 2021-02-14 - Written - Bovy (UofT)