A BLACK hole ejected from its host galaxy could be detected by bright flares emitted by a retinue of captured stars.
When two supermassive black holes collide, one or both may be hurled from the centre of the galaxy. Some such “recoiling” black holes can be detected by their accretion discs of swirling, glowing hot gas.
However, most black holes are stripped of their accretion discs as they are thrown into exile. And even if they keep their discs, the black holes can consume them within tens of millions of years, leaving nothing behind but a naked, invisible black hole.…
