Astronomers have long suspected that a distant quasar harbors not one but two supermassive black holes. They've now detected OJ 287's second black hole.
Astronomers have discovered a pair of supermassive black holes that whirl around each other every two years.
In the news this week: Globular clusters have the detailed scoop on our galaxy's past, and a "heartbeat" black hole binary in the Milky Way has gone mysteriously dim.
Astronomers think they’ve detected a flash created by the merger of two black holes.
A re-analysis of data from LIGO and Virgo brings the number of gravitational-wave detections to 11, including the most distant and most powerful black-hole merger yet discovered.
Supermassive black holes en route to merger have strange dynamics in their gas disks. Astronomers have spotted the most distant spectroscopically confirmed supernova. And NSF decides the fate of the Arecibo Observatory.