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

wgala.dynamics.PhaseSpacePosition, gala.dynamics.Orbit

potentialgala.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

actionsnumpy.ndarray

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

anglesnumpy.ndarray

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

freqsnumpy.ndarray

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