"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?
![The most energetic shock can be clearly seen around one of the galaxies, well-offset from the X-rays' peak intensity. Image credit: X-ray: NASA/CXC/SAO/R. van Weeren et al; Optical: NAOJ/Subaru; Radio: NCRA/TIFR/GMRT.](/files/startswithabang/files/2017/01/shock1-600x453.jpg)
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!
![A multiwavelength, annotated view shows the supermassive black holes and jets that have been activated by the collision. Image credit: X-ray: NASA/CXC/SAO/R. van Weeren et al; Optical: NAOJ/Subaru; Radio: NCRA/TIFR/GMRT.](/files/startswithabang/files/2017/01/a3411_label-600x412.jpg)
Go get the full story in pictures, videos and no more than 200 words on today’s Mostly Mute Monday!
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