Gamma Rays from Single-Lobe Supernova Explosions

Multidimensional simulations of the neutrino-driven mechanism behind core-collapse supernovae have long shown that the explosions from this mechanism would be asymmetric. Recently, detailed core-collapse simulations have shown that the explosion may be strongest in a single direction. We present a suite of simulations modeling these ``single-lobe'' supernova explosions of a 15 M<sub>solar</sub> red supergiant star, focusing on the effect these asymmetries have on the gamma-ray emission and the mixing in the explosion. We discuss how these asymmetries in the explosion mechanism might explain many of the observed ``asymmetries'' of supernovae, focusing on features of both supernova 1987A and the Cassiopeia A supernova remnant. In particular, we show that single-lobe explosions provide a promising solution to the redshifted iron lines of supernova 1987A. We also show that the extent of mixing for explosive burning products depends sensitively on the angular profile of the velocity asymmetry and may be much more extensive than previously assumed.