Are monster black holes marauding through the universe?

The article focuses on the possibility of wandering black holes in the universe. It discusses how a merger of two galaxies of different masses can leave the black hole of the smaller one stranded and astray in the outskirts of the bigger one. It is said that stray black holes are unlikely to intercept and eat a gas cloud or star to make them detectable. It adds that the merger of two galaxies with similar sizes can create gravitational waves that can kick the merged black hole out of its nest.