Secondary Photons from High-Energy Protons Accelerated in Hypernovae

Abstract

Recent observations show that hypernovae may deposit some fraction of their kinetic energy in mildly relativistic ejecta. In the dissipation process of such ejecta in a stellar wind, cosmic-ray protons can be accelerated up to ~10¹⁹ eV. We discuss the TeV to MeV gamma-ray and the X-ray photon signatures of cosmic rays accelerated in hypernovae. Secondary X-ray photons, emitted by electron-positron pairs produced via cascade processes due to high-energy protons, are the most promising targets for X-ray telescopes. Synchrotron photons emitted by protons can appear in the GeV band, requiring nearby (<40 Mpc) hypernovae for detection with GLAST. In addition, air Cerenkov telescopes may be able to detect regenerated TeV photons emitted by electron-positron pairs generated by CMB attenuation of π⁰-decay photons.