Using Monte Carlo codes, we follow the collisional evolution of clusters in a variety of scenarios. We consider the conditions under which a cluster of main-sequence stars may undergo rapid core collapse due to mass segregation, thus entering a phase of runaway collisions, forming a very massive star (VMS, M* > 1000M⊙) through repeated collisions between single stars. Although collisional mass loss is accounted for realistically, we find that a VMS forms even in proto-galactic nuclei models with a high velocity dispersion (many 100 kms−1). Such a VMS may be a progenitor for an intermediate-mass black hole (M� ≥ 100M⊙). In contrast, in galactic nuclei hosting a central massive black hole, collisions are found to be disruptive. The stars which are subject to collisions are progressively ground down by high-velocity collisions and a merger sequence appears impossible.
|Original language||English (US)|
|Title of host publication||Massive Stars in Interactive Binaries|
|Editors||Nicole St.Louis, Anthony F L Moffat|
|Publisher||Astronomical Society of the Pacific|
|Number of pages||7|
|State||Published - 2007|
|Name||Astronomical Society of the Pacific Conference Series|