GalPort: Investigation of the bar in action-angle space

Abstract

GalPort is a Python package for analysing the orbital dynamics of evolving disc galaxy numerical models in action-angle space. The package implements novel numerical methods for efficiently estimating actions, angles, and frequencies across different, particle-specific timescales: on the scale of radial or vertical oscillation and on the resonant libration/circulation timescale. The algorithm allows calculation of these dynamic quantities simultaneously at all time steps of the simulated galactic evolution. With this tool, one can trace orbital behaviour within time-varying galactic potentials and classify orbits (resonantly trapped, circulating, or passing through a resonance) based on their angle evolution. GalPort also includes specialised options for analysing the phase-space structure of a galactic bar in the disc plane and along its major axis. We demonstrate the package's performance on a typical N-body model of a barred galaxy, obtaining the global distributions of actions and frequencies and performing a detailed orbital decomposition. The code is publicly available under the MIT license at: https://github.com/vdzozulia/galport