The role of dark matter halos in the motion of stars in galaxies

Abstract

In this paper, we study the effects produced by a dark matter halo on the regular or chaotic nature of the orbits of a star moving near the galactic plane. The potential consists of three components: a spherical core, a disk and an ellipsoidal dark matter halo. We run simulations with three different halo shapes at three different energies. Using Poincaré sections we visually analyze the transition from regular to chaotic orbits and confrm that the shape of the dark halo is a key element: the spherical halo keeps the orbits stable, the prolate halo induces more chaotic orbits globally while the triaxial ellipsoid only does so at the core.