IsochronePotential

class gala.potential.IsochronePotential(m, b, units)

Bases: gala.potential.CPotentialBase

The Isochrone potential.

\[\Phi = -\frac{GM}{\sqrt{r^2+b^2} + b}\]

Parameters:

m : numeric

Mass.

b : numeric

Core concentration.

units : UnitSystem (optional)

Set of non-reducable units that specify (at minimum) the length, mass, time, and angle units.

Methods Summary

action_angle

Transform the input cartesian position and velocity to action-angle coordinates the Isochrone potential.

Methods Documentation

action_angle()

Transform the input cartesian position and velocity to action-angle coordinates the Isochrone potential. See Section 3.5.2 in Binney & Tremaine (2008), and be aware of the errata entry for Eq. 3.225.

This transformation is analytic and can be used as a “toy potential” in the Sanders & Binney 2014 formalism for computing action-angle coordinates in _any_ potential.

Adapted from Jason Sanders’ code here.

Parameters:

w : gala.dynamics.CartesianPhaseSpacePosition, gala.dynamics.CartesianOrbit

The positions or orbit to compute the actions, angles, and frequencies at.