King DF

class galpy.df.kingdf(W0, M=1.0, rt=1.0, npt=1001, ro=None, vo=None)[source]

Class that represents a King DF:

\[\begin{split}f(\mathcal{E}) = \begin{cases} \rho_1\,(2\pi\sigma^2)^{-3/2}\,\left(e^{\mathcal{E}/\sigma^2}-1\right), & \mathcal{E} > 0\\0, & \mathcal{E} \leq 0\end{cases}\end{split}\]

where \(\mathcal{E}\) is the binding energy. See also King potential.

__init__(W0, M=1.0, rt=1.0, npt=1001, ro=None, vo=None)[source]

Initialize a King DF

Parameters:

  • W0 (float) – Dimensionless central potential \(W_0 = \Psi(0)/\sigma^2\) (in practice, needs to be \(\lesssim 200\), where the DF is essentially isothermal).

  • M (float or Quantity, optional) – Total mass.

  • rt (float or Quantity, optional) – Tidal radius.

  • npt (int, optional) – Number of points to use to solve for \(\Psi(r)\).

  • 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

  • 2020-07-09 - Written - Bovy (UofT)