Ultra-high energy cosmic rays from supermassive black holes: particle flux on the Earth and extragalactic diffuse emission

Cosmic rays accelerated to ultra-high energies (E >4⋅10¹⁹ eV) in electric fields in accretion discs around supermassive black holes are discussed. Particle injection spectra are assumed to be harder than those formed in acceleration at shock fronts. It turned out that cosmic rays with injection spectra supposed contribute a little in the particle flux detected with ground-based arrays. But in the extragalactic space particles generate a noticeable flux of the diffuse gamma-ray emission compared with the data obtained with Fermi LAT instrument (onboard the Fermi space observatory). The intensity of neutrinos generated by cosmic rays propagating in the extragalactic space is also derived. The model intensity of cascade neutrinos is much lower than that of astrophysics neutrino. It is concluded that possibly supermassive black holes are cosmic ray sources which contribute slightly to the particle flux detected on the Earth, but these sources should be taken into account analyzing components of extragalactic diffuse gamma-ray emission. (paper)