  The origin of ultrahigh-energy cosmic rays (UHECRs) is a half-century old
enigma (Linsley 1963). 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 (Murase and Waxman 2016).
Here we report that powerful black hole jets in aggregates of galaxies can
supply the common origin of 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.
