It can be done, and has been done by several bow hunters. I would try to use as heavy of a bow you can shoot, and heavier arrows also. Do some reaserch, I know Chuck Adams and a few pople like him have done it. And I know there used to be a free ranging huntable herd in the Henry Mountains of Utah, that was a draw hunt for the public. I think there may be a couple other places also? But in the end yes a bow will kill a bison just fine. I think I would want a partner with some sort of a back up weapon (if leagal?) for a just in case scenerio?
Good luck
Buck