I think the picture shows more realism than the artist's impression. You can't see the gamma-ray beam actually coming from the first galaxy's black hole, only the spot where it lights up the other galaxy, and a sort of smoke-plume (glowing in radio-waves) flying out as a result. Pretty much what you'd see if you shot something with a high-power laser/particle beam. It's a good picture, showing a lot of space-destruction.