Ultra-High Energy Cosmic Rays and the GeV-TeV Diffuse Gamma-Ray Flux

Understand

Ultra-high energy cosmic ray protons accelerated in astrophysical objects produce secondary electromagnetic cascades during propagation in the cosmic microwave and infrared backgrounds.

• We show that such cascades can contribute between ~1% and ~50% of the GeV-TeV diffuse photon flux measured by the EGRET experiment.
• The GLAST satellite should have a good chance to discover this flux.