RE-EXAMINATION OF THE EXPECTED GAMMA-RAY EMISSION OF SUPERNOVA REMNANT SN 1987A

Abstract

A nonlinear kinetic theory, combining cosmic-ray (CR) acceleration in supernova remnants (SNRs) with their gas dynamics, is used to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5-50 yr. This spherically symmetric model is approximately applied to the different features of the SNR which consist of (i) a blue supergiant wind and bubble, and (ii) of the swept-up red supergiant (RSG) wind structures in the form of an H II region, an equatorial ring (ER), and an hourglass region. The RSG wind involves a mass loss rate that decreases significantly with elevation above and below the equatorial plane. The model adapts recent three-dimensional hydrodynamical simulations by Potter et al. in 2014 that use a significantly smaller ionized mass of the ER than assumed in the earlier studies by the present authors. The SNR shock recently swept up the ER, which is the densest region in the immediate circumstellar environment. Therefore, the expected gamma-ray energy flux density at TeV energies in the current epoch has already reached its maximal value of $\sim 10^{-13}$ erg cm$^{-2}$ s$^{-1}$. This flux should decrease by a factor of about two over the next 10 years.