Prompt and delayed high-energy emission from cosmological gamma-ray bursts

Abstract In the cosmological blast-wave model for gamma ray bursts (GRBs), high energy (≳ 10 GeV) γ-rays are produced either through Compton scattering of soft photons by ultrarelativistic electrons, or as a consequence of the acceleration of protons to ultrahigh energies. We describe the spectral and temporal characteristics of high energy γ-rays produced by both mechanisms, and discuss how these processes can be distinguished through observations with low-threshold Cerenkov telescopes or GLAST. We propose that Compton scattering of starlight photons by blast wave electrons can produce delayed flares of GeV-TeV radiation.