The nature of orbits in a prolate elliptical galaxy model with a bulge and a dense nucleus

TL;DR

This study investigates how stars move in a prolate elliptical galaxy model with a bulge and dense nucleus, revealing how physical parameters influence the transition from regular to chaotic orbits.

Contribution

It identifies relationships between galaxy parameters and the critical angular momentum for chaos, providing theoretical explanations for these dynamics.

Findings

Inverse square law between bulge radius and critical angular momentum

Linear relationship between nucleus mass and critical angular momentum

Connections between orbital chaos and galaxy physical parameters

Abstract

We study the transition from regular to chaotic motion in a prolate elliptical galaxy dynamical model with a bulge and a dense nucleus. Our numerical investigation shows that stars with angular momentum Lz less than or equal to a critical value Lzc, moving near the galactic plane, are scattered to higher z, when reaching the central region of the galaxy, thus displaying chaotic motion. An inverse square law relationship was found to exist between the radius of the bulge and the critical value Lzc of the angular momentum. On the other hand, a linear relationship exists between the mass of the nucleus and Lzc. The numerically obtained results are explained using theoretical arguments. Our study shows that there are connections between regular or chaotic motion and the physical parameters of the system, such as the star's angular momentum and mass, the scale length of the nucleus and the radius of the bulge. The results are compared with the outcomes of previous work.