On what basis was he placed under house arrest and shown the insrtuments of torture?
As I said, for telling theologians that their interpretation of scripture was incorrect before he adequately could back it up. At that time many Jesuit astronomers actually supported the Copernican model, but didn't change their theology based on it just them because there wasn't a consensus. At one point he was even told he could research whatever he wanted, but to "stay out of the sacristy".