Prospects for gamma-ray line observations of individual supernovae

Abstract

The gamma-ray line emission from individual type I and type II supernovae are studied using numerical simulations and photon propagation codes to predict the flux levels and line shapes. For both types, the gamma ray lines with the highest flux from an individual event are the 0.847 and 1.238 MeV lines from the Ni-56 to Co-56 to Fe-56 decay chain. For type I supernovae, the 0.847 MeV line peaks at about 70 days after event onset. The historical record indicates an approximate discovery rate of once in 10 years for balloon-borne instruments, once in two to three years for the Gamma-Ray Observatory, and once in one to two years for a proposed space mission. The 0.847 MeV line flux from type II supernovae peaks at about 600 days after event onset at a low level which restricts observations to the events in the Galaxy and its nearest neighbors. The expected line shape is narrower than for type I supernovae.