King potential

class galpy.potential.KingPotential(W0=2.0, M=3.0, rt=1.5, npt=1001, _sfkdf=None, ro=None, vo=None)[source]

Potential of a King profile, defined from the distribution function

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

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

__init__(W0=2.0, M=3.0, rt=1.5, npt=1001, _sfkdf=None, ro=None, vo=None)[source]

Initialize a King potential

Parameters:

  • W0 (float, optional) – Dimensionless central potential W0 = Psi(0)/sigma^2 (in practice, needs to be <~ 200, where the DF is essentially isothermal). Default: 2.

  • M (float or Quantity, optional) – Total mass. Default: 1.

  • rt (float or Quantity, optional) – Tidal radius. Default: 1.

  • npt (int, optional) – Number of points to use to solve for Psi(r) when solving the King DF. Default: 1001.

  • 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

  • 2020-07-11 - Written - Bovy (UofT)