Neutrons, rotating black holes, and a galactic PeVatron at the center of the Milky Way‎

Galactic black holes are cosmic mitochondria, powerhouses of the universe. Most of the energy these supermassive black holes produce comes from the material surrounding them: superheated plasma in their accretion disks interacting with tremendous magnetic fields. But there is a more direct way to extract energy from a black hole. It's known as the Penrose process, and a new study asks whether we could discover a signature of this process.