isochrone_to_aa

gala.dynamics.isochrone_to_aa(w, potential)

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

Note

This function is included as a method of the IsochronePotential and it is recommended to call phase_space() instead.

Parameters:

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

potential : gala.potential.IsochronePotential, dict

An instance of the potential to use for computing the transformation to angle-action coordinates. Or, a dictionary of parameters used to define an gala.potential.IsochronePotential instance.

Returns:

actions : numpy.ndarray

An array of actions computed from the input positions and velocities.

angles : numpy.ndarray

An array of angles computed from the input positions and velocities.

freqs : numpy.ndarray

An array of frequencies computed from the input positions and velocities.