Black holes in binary stars could be the galaxy's ultrahigh-energy particle factories

Where do the most energetic cosmic rays come from? LHAASO recently detected PeV-scale gamma rays from microquasars—black holes feeding on companion stars—suggesting they're powerful particle accelerators. The authors show a two-population model fits observations: supernova remnants dominate below 100 TeV, then microquasars take over at higher energies. This resolves a decade-long puzzle about PeVatrons and matches proton, helium, and full composition data up to the knee region.