Generally, black holes spin really fast, roughly at the speed of light. However, astronomers have detected that one monster black hole is spinning relatively slower than most smaller black holes.
The discovery may disclose clues about the way these supermassive black holes are created. Located at the heart of quasar H1821+643, roughly 3.4 billion light-years from Earth, this supermassive black hole is between 3 billion and 30 billion solar masses, making it one of the most enormous black holes scientists have ever found out. After evaluating the data from NASA’s Chandra X-ray Observatory, the scientists measured how fast the monster black hole was spinning.
“We found that the black hole in H1821+643 is spinning about half as quickly as most black holes weighing between about a million and 10 million suns,” Christopher Reynolds, an astronomer at the University of Cambridge and co-author of a study describing the results, announced in a statement. “The million-dollar question is, why?”
One leading assumption implies that supermassive black holes are created by collisions between two smaller black holes. During the violent merger, the black holes may suffer dramatic changes in a spin as the gravitational forces pull the black holes in different directions, which could result in the supermassive black hole spinning slower. Smaller black holes (non-supermassive ones), on the other hand, are believed to form as they amass material from a disk of gas that encircles them, which provides their spin in a single direction, enabling the black holes to gain speed quickly.