X-ray: CXC/NASA; Optical: STScI/NASA
A chance alignment of a bright, distant galaxy behind a much closer one has given astronomers a rare opportunity to determine the spin of a supermassive black hole 6 billion light-years from Earth.
The alignment of the galaxies, a phenomenon called a gravitational lens, magnified and split the light coming from matter falling into the more distant galaxy's supermassive black hole. From the four split images, astronomers were able to calculate that the supermassive black hole spins at nearly half the speed of light, which is considered relatively fast.
The new study is the first to measure the spin of a supermassive black hole that is roughly 7 billion years old and the first to suggest that supermassive black holes from this time acquire matter consistently rather than chaotically, the team reports March 5 in Nature.