High redshift formation and evolution of central massive objects I:
  model description
  Galactic nuclei host central massive objects either in the form of
supermassive black holes or nuclear stellar clusters. Recent investigations
have shown that both components co-exist in at least a few galaxies. In this
paper we explore the possibility of a connection between nuclear star clusters
and black holes that establishes at the moment of their formation. We here
model the evolution of high redshift discs, hosted in dark matter halos with
virial temperatures 10^4 K, whose gas has been polluted with metals just above
the critical metallicity for fragmentation. A nuclear cluster forms as a result
of a central starburst from gas inflowing from the unstable disc. The nuclear
stellar cluster provides a suitable environment for the formation of a black
hole seed, ensuing from runaway collisions among the most massive stars.
Typical masses for the nuclear stellar clusters at the time of black hole
formation (z~10) are inthe range 10^4-10^6 solar masses and have half mass
radii < 0.5 pc. The black holes forming in these dense, high redshift clusters
can have masses in the range ~300-2000 solar masses.
