2020RNAAS...4..115C

Already in the first days after the explosion of a supernova, the strong shock expanding forward into the dense wind of the progenitor star can theoretically accelerate particles up to the ∼PeV (=10¹⁵ eV) range. These accelerated particles, interacting with the dense wind material, should lead to the production of gamma-rays in the 1-100 TeV range, through pion production. However, no supernova has yet been detected by current Cerenkov instruments, and the question of the detectability of extragalactic supernovae in nearby galaxies (within a few Mpc) by next generation instruments is still open. The detection in the TeV range is especially hindered by the two-photon annihilation process, in which high-energy gamma-rays interact with soft photons from the photosphere to produce electron/positron pairs, thereby degrading the gamma-ray signal from the system. We calculate the temporal evolution of the expected gamma-ray attenuation in the well-studied type IIb SN 1993J, accounting for both temporal and geometrical effects.