Observe Gamma-Rays and Neutrinos Associated with Ultra-High Energy Cosmic Rays

IceCube measures a diffuse neutrino flux comparable to the Waxman-Bahcall bound, which suggests possibility that ultra-high energy cosmic rays (UHECRs) have common origin with high neutrinos. We propose gamma-ray and/or observations toward arrival directions of UHECRs search for sources and test this possibility. calculate detection probability gamma-ray/neutrino sources, find average per UHECR >10 EeV is ∼10% if sensitivity or telescope ∼10−12 erg cm−2 s−1 source number density ∼10−5 Mpc−3. Future UHECRs, e.g., by LHAASO-WCDA, CTA, IceCube/Gen2, are encouraged constrain even identify UHECRs.