"Speculating and predicting what lies beyond the boundary is fascinating. Finding out is even more fascinating." -Wallace H. Tucker
When two galaxy clusters collide, there are a slew of cosmic certainties you can bet on: all the galaxies will miss one another, the intracluster gases will collide and heat up, and X-rays will be emitted. But on rare occasion, radio emission can be found, too. Which is a puzzle, since that requires electrons to gain an extra factor of 1,000,000 in energy! How can that happen?
Up until recently, it was a mystery, but a new colliding cluster, Abell 3411 and 3412, has shown something incredible: gas shocks on the outskirts of the X-ray collisions appear to get a blast from nearby, active supermassive black holes, giving the electrons the needed boost and creating those energetic electrons after all!