Secondary Photons from High-energy Protons Accelerated in Hypernovae

TL;DR

Hypernovae can accelerate protons to ultra-high energies, producing detectable gamma-ray and X-ray signatures through cascade processes, with potential observations by current and future telescopes.

Contribution

This paper explores the gamma-ray and X-ray signatures from cosmic rays accelerated in hypernovae, highlighting observable secondary photons across multiple energy bands.

Findings

Secondary X-ray photons from cascades are promising for X-ray telescope detection.

Protons can produce GeV synchrotron photons detectable within 40 Mpc.

Regenerated TeV photons may be observed by air Cherenkov telescopes.

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 $\sim 10^{19}$ 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 Cherenkov telescopes may be able to detect regenerated TeV photons emitted by electron-positron pairs generated by CMB attenuation of $\pi^0$ decay photons.