Dark halos acting as chaos controllers in asymmetric triaxial galaxy models

TL;DR

This study investigates how dark halos influence the chaos in orbits within a triaxial galaxy model, revealing that increasing halo mass reduces chaos and introducing a new, efficient chaos indicator based on total angular momentum.

Contribution

The paper introduces a new chaos indicator using total angular momentum and demonstrates its effectiveness compared to traditional methods in galactic dynamics.

Findings

Chaos decreases exponentially with increasing halo mass.

Chaos increases linearly with halo scale length.

The Ltot indicator is fast and reliable for orbit classification.

Abstract

We study the regular or chaotic character of orbits in a 3D dynamical model, describing a triaxial galaxy surrounded by a spherical dark halo component. Our numerical experiments suggest that the percentage of chaotic orbits decreases exponentially as the mass of the dark halo increases. A linear increase of the percentage of the chaotic orbits was observed as the scale length of the halo component increases. In order to distinguish between regular and chaotic motion, we chose to use the total angular momentum Ltot of the 3D orbits as a new indicator. Comparison with other, previously used, dynamical indicators, such as the Lyapunov Characteristic Exponent or the P(f) spectral method, shows that the Ltot indicator gives very fast and reliable results for characterizing the nature of orbits in galactic dynamical models.