Strange Unexplained Cosmic Rays (ft PhD Comics)

You get a gaussian distribution of energies from just about any source . These high energy particles are clearly at the high end which is why they are so rare. I suspect particles bumped up in energy near black holes. You get a log jam of sorts, everything can't make it into the hole faster than what's coming in behind so some of the stuff gets pushed up to high enough energy to escape and a few that get really bumbed up. Since the stuff is already orbiting near light speed near the event horizon that's quite a potent engine.