This is a great video (compliments of Spacerip) displaying excellent computer simulations on how the largest black holes in the universe form. These Super-massive black holes are thought to be the result of the merging of 2 other black holes. Simulations shown in this video are based on theories from x-ray, infra-red and visible light images of actual black holes.
The largest known super-massive black holes are approximately 21 Billion solar masses (21 billion times the size of our Sun!).
This video is one of the best I have seen in describing the creation of super-massive black holes supported by actual images. The graphics and computer simulations are exquisite.
Maddalena Environmental Inc.