As I understand it, it's all atomic material in the accretion disk of a big black hole, with very high orbital velocities and high density. However, the the disk is quite flat, and cooler than one would think with the velocities involved, because the material is swirling in smoothly, with individual particles having fairly tame velocities relative to nearby particles. Now, I have two questions, really. First, does my understanding of the very basic properties of accretion disks agree with the currently accepted models? And second, is it possible for fusion to occur in the inner area of the disk? I know that the temperature of the gas is only on the order of x-ray emission, too cool for fusion, but what if there was some sort of perturbation in the disk, something that disrupted it's very smooth inward spiral. To me it seems like with the densities and energies involved, it would be a good environment for nuclear fusion. So, is there any merit to this idea?