How to Spot the Speediest Black Holes

Astronomers are hunting an elusive target: rogue black holes that have been ejected from the centers of their home galaxies. Some doubted that the quarry could be spotted, since a black hole must be gobbling matter from an accretion disk in order for that matter to shine. And if a black hole is ripped from the core of its home galaxy and sent hurling into the outskirts, the thinking goes, then its accretion disk might be left behind.