Origin of supermassive black holes in massive metal-poor protoclusters
  While large numbers of supermassive black holes have been detected at z>6,
their origin is still essentially unclear. Numerical simulations have shown
that the conditions for the classical direct collapse scenario are very
restrictive and fragmentation is very difficult to be avoided. We thus consider
here a more general case of a dense massive protostar cluster at low
metallicity (<~ 10^{-3} Z_solar) embedded in gas. We estimate the mass of the
central massive object, formed via collisions and gas accretion, considering
the extreme cases of a logarithmically flat and a Salpeter-type initial mass
function. Objects with masses of at least 10^4 solar could be formed for
inefficient radiative feedback, whereas ~10^3 solar mass objects could be
formed when the accretion time is limited via feedback. These masses will vary
depending on the environment and could be considerably larger, particularly due
to the continuous infall of gas into the cloud. As a result, one may form
intermediate mass black holes of ~ 10^4 solar masses or more. Upcoming
observations with the James Webb Space Telescope (JWST) and other observatories
may help to detect such massive black holes and their environment, thereby
shedding additional light on such a formation channel.
