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We use numerical simulations to explore whether direct collapse can lead tothe formation of SMBH seeds at high-z. We follow the evolution of gas within DMhalos of 2 x 10^8 Mo and 1 kpc. We adopt cosmological density profiles andj-distributions. Our goal is to understand how the collapsing flow overcomesthe centrifugal barrier and whether it is subject to fragmentation. We findthat the collapse leads either to a central runaway or to off-centerfragmentation. A disk-like configuration is formed inside the centrifugalbarrier. For more cuspy DM distribution, the gas collapses more and experiencesa bar-like perturbation and a central runaway. We have followed this inflowdown to ~10^{-4} pc. The flow remains isothermal and the specific angularmomentum is efficiently transferred by gravitational torques in a cascade ofnested bars. This cascade supports a self-similar, disk-like collapse. In thecollapsing phase, virial supersonic turbulence develops and fragmentation isdamped. For larger initial DM cores the timescales become longer. In modelswith more organized initial rotation, a torus forms and appears to be supportedby turbulent motions. The evolution depends on the competition between twotimescales, corresponding to the onset of the central runaway and off-centerfragmentation. For less organized rotation, the torus is greatly weakened, thecentral accretion timescale is shortened, and off-center fragmentation issuppressed --- triggering the central runaway even in previously `stable'models. The resulting SMBH masses lie in the range 2 x 10^4 Mo - 2 x 10^6 Mo,much higher than for Population III remnants. We argue that the above upperlimit appears to be more realistic mass. Corollaries of this model include apossible correlation between SMBH and DM halo masses, and similarity betweenthe SMBH and halo mass functions, at time of formation.

Supermassive Black Hole Formation at High Redshifts via Direct Collapse: Physical Processes in the Early Stage