PeV gamma rays from interactions of ultra high energy cosmic rays in the Milky Way

The PeV gamma ray background produced in the interactions of ultra high energy cosmic rays with the ambient matter and radiations during their propagation in the Milky Way has been calculated in this paper. If the primary ultra high energy cosmic rays are produced from Galactic point sources then those point sources are also emitting PeV gamma rays. We discuss that the detection of galactocentric PeV gamma rays in the future would be a signature of the presence of EeV cosmic accelerators in the Milky Way.

► PeV–EeV γ rays from interactions of diffuse UHECRs with matter and radiations in the Milky Way.
► Their event rates estimated in km2 yr.
► Mean free path of pair production in recently measured radio background has been calculated.
► Galactocentric PeV γ rays above the background would be signatures of Galactic origin of EeV UHECRs.