Astronomers have found stellar mass and supermassive black holes, but they're still on the hunt for an intermediate size; black holes with thousands of times the mass of the Sun. One natural place to look is at the heart of the Milky Way, near our galaxy's supermassive black hole. Researchers have examined the region around the galactic core and the movement of stars whipping around the central black hole. Although they didn't find evidence for a companion black hole, they've set size constraints on what could be there.