King potential

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

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)

NAME:

__init__

PURPOSE:

Initialize a King potential

INPUT:

W0= (2.) dimensionless central potential W0 = Psi(0)/sigma^2 (in practice, needs to be <~ 200, where the DF is essentially isothermal)

M= (1.) total mass (can be a Quantity)

rt= (1.) tidal radius (can be a Quantity)

npt= (1001) number of points to use to solve for Psi(r) when solving the King DF

ro=, vo= standard galpy unit scaling parameters

OUTPUT:

(none; sets up instance)

HISTORY:

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