Angle-action estimation in a general axisymmetric potential

TL;DR

This paper introduces a new method for estimating angle-action variables in realistic axisymmetric galaxy potentials by locally fitting a Stäckel potential, improving analysis of stellar orbits in the Milky Way.

Contribution

A novel local fitting technique for angle-action estimation in realistic galaxy potentials, validated against existing methods and applied to survey data.

Findings

The method accurately estimates angle-action variables for various orbit types.

Comparison shows improved performance over previous approaches.

Application to Geneva-Copenhagen survey demonstrates practical utility.

Abstract

The usefulness of angle-action variables in galaxy dynamics is well known, but their use is limited due to the difficulty of their calculation in realistic galaxy potentials. Here we present a method for estimating angle-action variables in a realistic Milky Way axisymmetric potential by locally fitting a St\"ackel potential over the region an orbit probes. The quality of the method is assessed by comparison with other known methods for estimating angle-action variables of a range of disc and halo-type orbits. We conclude by projecting the Geneva-Copenhagen survey into angle-action space.