Astronomers Measure Supermassive Black Hole's Spin Using Destroyed Star
For the first time, astronomers have measured the spin of a supermassive black hole using the wobble of a hot accretion disk formed from a star that was torn apart by the black hole. The event, known as AT2020ocn, revealed that the black hole's spin is less than one-quarter of the speed of light. This discovery, made using the NICER telescope, provides new insights into the growth and evolution of supermassive black holes.