Dynamical friction on globular clusters in core-triaxial galaxies: is it a cause of massive black hole accretion?

Abstract

The present work extends and deepens previous examinations of the evolution of globular cluster orbits in elliptical galaxies, by means of numerical integrations of a wide set of orbits in five self-consistent triaxial galactic models characterized by a central core and different axial ratios. These models are valid and complete in the representation of regular orbits in elliptical galaxies. Dynamical friction is definitely shown to be an efficient cause of evolution for the globular cluster systems in elliptical galaxies of any mass or axial ratio. Moreover, our statistically significant sample of computed orbits confirms that the globular cluster orbital decay times are, at least for clusters moving on box orbits, much shorter than the age of the galaxies. Consequently, the mass carried into the innermost galactic region in the form of decayed globular clusters may have contributed significantly to feeding and accreting a compact object therein

Merging of Globular Clusters in Inner Galactic Regions. II. Nuclear Star Cluster Formation

“…The answers to these questions are of overwhelming importance to give substance to the interpretation of the formation of early-type galaxy nuclei via merging of decayed GCs, a hypothesis first raised by Tremaine et al (1975) and subsequently extensively studied by Capuzzo-Dolcetta (1993), Capuzzo-Dolcetta & Tesseri (1997), and Capuzzo-Dolcetta & Vicari (2005.…”

Star cluster dynamics in galaxies

“…Previous theoretical studies discussed the formation of stellar galactic nuclei through mergers of SCs (or GCs) in galaxies with different physical properties (e.g., Lotz et al 2001;Capuzzo-Dolcetta & Vicari 2005). Recent, fully self-consistent N -body simulations have shown that mergers of SCs in the inner regions of galaxies lead to the formation of stellar galactic nuclei with projected radial density profiles similar to what is observed (e.g., Capuzzo-Dolcetta & Miocchi 2008).…”

“…Equally, basic galactic components such as stellar galactic nuclei and thin and thick disks can also be influenced dynamically by the evolution of SC systems (e.g., Kroupa 1998;Capuzzo-Dolcetta & Vicari 2005). Radial density profiles of the stars in individual SCs formed from GMCs may depend on the strength of the tidal field of their host galaxy (e.g., Hurley & Bekki 2008).…”

Galactic nuclei formation and activity induced by globular cluster merging

“…This difference in the density profiles has an interpretation either in terms of formation and evolution of elliptical galaxies (see [20], [17], [1], [3]). or in terms of evolution of the GCS itself (see [4], [13], [14]). The explanation on the basis of GCS evolution is more appealing, because much simpler and not based on qualitative and arbitrary modelizations of GC formation in galaxies.…”