Global dynamics in a self--consistent model of elliptical galaxy

Abstract

In the present paper we study the global dynamics corresponding to a realistic model of self-consistent triaxial galactic system. We extend a previous work [17] where the authors investigate 3,472 orbits in this model at different energy levels, using Lyapunov exponents to measure chaoticity and frequency analysis to classify regular orbits. Here we first display the main properties of that potential and then focus our attention on the global dynamical features of the box domain for nine energy surfaces. Using the MEGNO as a fast dynamical indicator, we gain insight in the resonance structure at different energy levels, the way in which relatively large chaotic domains arise due to overlapping as well as crossings of resonances and we measure the fraction of chaotic motion in the energy space. It is interesting to notice that the flatness of the model varies over a rather wide range, namely from ~ $0.5$ to ~ $1$, and the fraction of chaotic motion ranges from ~ $0.15$ at small energies up to ~ $0.75$ at moderate values of the energy, decreasing then again down to values close to ~ $0.4$ where the system becomes nearly spherical.