While solitary black holes should be common, they are hard to find. The one in Sagittarius revealed itself when it passed in front of a dim background star, magnifying the star’s light and slowly ...

A distant galaxy that lay quiet for decades has suddenly stirred, lighting up in dramatic bursts that have caught astronomers ...

XMM-Newton proved particularly critical to studying Ansky’s behavior, since it is the only telescope sensitive enough to capture fainter background X-ray light amid the black hole’s stronger X ...

A black hole in a distant galaxy has kept astronomers hooked to its quasiperiodic eruption activity, which is not a regular phenomenon.