The origin of ultrahigh-energy cosmic rays (UHECRs) is a half-century-old enigma. The mystery has been deepened by an intriguing coincidence: over ten orders of magnitude in energy, the energy generation rates of UHECRs, PeV neutrinos and isotropic sub-TeV gamma-rays are comparable, which hints at a grand unified picture.
Here we report that powerful black hole jets in aggregates of galaxies can supply the common origin for all of these phenomena. Once accelerated by a jet, low-energy cosmic rays confined in the radio lobe are adiabatically cooled; higher-energy cosmic rays leaving the source interact with the magnetized cluster environment and produce neutrinos and gamma-rays.
The highest-energy particles escape from the host cluster and contribute to the observed cosmic rays above 100 PeV. The model is consistent with the spectrum, composition and isotropy of the observed UHECRs, and also explains the IceCube neutrinos and the non-blazar component of the Fermi gamma-ray background, assuming a reasonable energy output from black hole jets in clusters.
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