Gamma-rays and X-rays from SN1987A

Abstract

Detections of γ-rays¹ and X-rays^2,3 from Supernova 1987A, together with its exponential light curve⁴, have dramatically confirmed theoretical predictions made two decades ago^5–7. We discuss what these observations, in August and September 1987, can already tell us about the supernova. Assuming that all of the high-energy photons originate from ⁵⁶Co decay, the escaping photon intensities at various energies are related by the characteristics of the scattering medium and the physics of the scattering processes. Considering only these factors, we conclude that the total mass of ⁵⁶Co implied by the light curve is not uniformly shielded by a thick envelope. Extensive 'mixing' of ⁵⁶Co (initially ⁵⁶Ni) and other heavy elements through the supernova envelope might explain the observations. It is likely that a small fraction of the ⁵⁶Co mass implied by the light curve has been removed by some mechanism to nearly thin regions.