Are there dark doings near the center of the Milky Way? That may be so when it comes to the collision of dark matter particles. Although such particles are invisible, we could still theoretically see the mess they make when they collide. It’s this idea that leads physicists to scour the galaxy for some glimmer of dark matter collisions. Spot a line produced by a pair of gamma-rays emanating from just the right spot and you may have found coveted clues to the dark matter mystery.
For the rest of the story: http://blogs.scientificamerican.com/observations/2012/11/18/strange-signal-at-galactic-center-is-it-dark-matter/