This causes a shock wave which blasts its way out through the infalling material, colliding with outer layers of the star as it does so. (newscientist.com)
The X-rays shown in red are from the supernova material itself - the outer layers of the star expanding outward behind the shock wave. (discovermagazine.com)
«Jets of material then hit the expanding outer layers of the star to produce the gamma - ray emission.» (discovermagazine.com)