Yes, there really is a black hole on the loose in Sagittarius

Astronomers have confirmed the first-ever detection of a solitary black hole, located 5,000 light-years away in the constellation Sagittarius. The object, about seven times as massive as the sun, was discovered when it passed in front of a background star, magnifying its light and shifting its position. This discovery is significant because all previously known stellar-mass black holes had companion stars. The finding opens up possibilities for detecting more lone black holes using future space telescopes.