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

Abstract

Cosmic rays accelerated to ultra-high energies (E >4•10 19 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 groundbased 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.

Using the “least-deflected” subsamples of ultra-high energy cosmic rays to constrain source population(s)

“…In order to test for a multimessenger signature in UHECR arrival directions, we correlate our UHECR simulation results with the directions of high-energy muon neutrinos. If indeed UHECRs and high energy neutrinos are produced simultaneously, then a candidate site for UHECR acceleration is the accretion disk around massive black holes (Uryson 2019;Tursunov et al 2020). A motivation for testing this scenario has been boosted by the multi-messenger detection of high energy neutrinos and γ-rays from the blazar TXS 0506+056 (IceCube Collaboration 2018).…”