Models of cuspy triaxial stellar systems. IV: Rotating systems

TL;DR

This paper presents self-consistent models of rotating, triaxial, cuspy stellar systems, analyzing their orbital content, stability, and the effects of rotation on their shape and orbital structure.

Contribution

It introduces new rotating models of cuspy triaxial stellar systems with detailed orbital analysis and stability assessment, extending previous non-rotating models.

Findings

Models are stable over a Hubble time despite high chaos.

Rotation causes flattening and triaxiality in the models.

Presence of unique regular orbits like horseshoes and crossing orbits.

Abstract

We built two self-consistent models of triaxial, cuspy, rotating stellar systems adding rotation to non-rotating models presented in previous papers of this series. The final angular velocity of the material is not constant and varies with the distance to the center and with the height over the equator of the systems, but the figure rotation is very uniform in both cases. Even though the addition of rotation to the models modifies their original semiaxes ratios, the final rotating models are considerably flattened and triaxial. An analysis of the orbital content of the models shows that about two thirds of their orbits are chaotic yet the models are very stable over intervals of the order of one Hubble time. The bulk of regular orbits are short axis tubes, while long axis tubes are replaced by tubes whose axes lie on the short-long axes plane, but do not coincide with the major axis. Other types of regular orbits that do not appear in non-rotating systems, like horseshoes and orbits that cross themselves, are also found in the present models. Finally, our frequency maps show empty regions where studies of orbits on fixed potentials found orbits, a likely consequence of the self-consistency of our models that excludes them.