N-body models of rotating globular clusters

• Published in: Monthly notices of the Royal Astronomical Society 2007-05, Vol.377 (2), p.465-479
• Main Authors: Ernst, A., Glaschke, P., Fiestas, J., Just, A., Spurzem, R.
• Format: Article
• Language: English
• Subjects: Astronomy; Cosmology; Earth, ocean, space; Exact sciences and technology; globular clusters: general; methods: N-body simulations; Simulation; Stars & galaxies; stellar dynamics
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2007.11602.x

In this paper we examine the dynamical evolution of rotating globular clusters with direct N-body models. Our initial models are rotating King models, and we obtain results both for equal-mass systems and for systems composed of two mass components. Previous investigations using a Fokker–Planck solver have shown that rotation has a noticeable influence on stellar systems such as globular clusters that evolve by two-body relaxation. In particular, it accelerates their dynamical evolution through the gravogyro instability. We have validated the occurrence of the gravogyro instability with direct N-body models. In the case of systems composed of two mass components, mass segregation takes place, a process that competes with the rotation in the acceleration of the core collapse. The ‘accelerating’ effect of rotation was detected in our isolated two-mass N-body models. Finally, we look at rotating N-body models in a tidal field within the tidal approximation. It turns out that rotation increases the escape rate significantly. A difference between retrograde- and prograde-rotating stellar clusters, with respect to the orbit of the cluster around the Galaxy, occurs. This difference is the result of the presence of a ‘third integral’ and chaotic scattering, respectively.