To power the rays, Blandford says, an AGN's central black hole would have to produce a massive electric field very far from itself, because otherwise the cauldron of photons around the hole would scatter the cosmic rays and blunt their energy.
He adds researchers would never have guessed that black holes might have such powers if not for high-energy cosmic rays. "Nature does tricks we didn't know were possible," he says. "But it is happening and it's marvelous." Auger should eventually pinpoint the rays' origins definitively, he says. "They have the capacity to answer these questions beyond all reasonable doubt."