A South Philadelphia man was arrested Friday in connection with a bank robbery and bomb threat the day before in Center City. Police said Paul Raffa, 32, of Snyder Avenue near Third Street, walked into a PNC Bank branch near 11th and Market Streets about 3 p.m. Thursday and slid a threatening note to a teller, police said. He demanded money and said he was carrying a bomb in his bag. Police said Raffa left his bag in the bank and fled with $3,000 in cash. Market Street between 11th and 12th was closed until about 4 p.m. while authorities investigated the bag Raffa left behind. They eventually found that it contained a water bottle, and they reopened Market Street to pedestrians and vehicles.