Talk detail

Participant	Davies, Melvyn
Institution	Lund Observatory - Box 43 - Lund - Skåne - Sweden

Session	EG4	Accepted		Order	Time
Talk	Oral abstract	Title	Supermassive Black Hole Formation in Nuclear Stellar Clusters
Co-authors
Abstract	Black holes exceeding a billion solar masses have been detected at redshifts greater than six. The rapid formation of these objects may suggest a massive early seed or a period of growth faster than Eddington. We propose that in the process of hierarchical structure assembly, dense star clusters can be contracted on dynamical timescales due to the nearly free-fall inflow of self-gravitating gas with a mass comparable to or larger than that of the clusters. This leads to core collapse where the cluster core can reach a central density high enough for fast mergers of stellar-mass black holes producing a supermassive black hole seed. We also consider the formation of supermassive black holes in nuclear stellar clusters at later times. We suggest that above a critical velocity dispersion ~ 40 km/s, massive central black holes will form in relaxed stellar systems. This is because above this dispersion primordial binaries cannot support the system against deep core collapse.