Measuring the spin of a distant black hole
DOI: 10.1063/PT.5.027740
Ars Technica : Thanks to a fortuitous alignment of another galaxy with a distant quasar, scientists were able to use the galaxy as a gravitational lens to magnify and examine the gas that swirls around the quasar’s supermassive black hole. From data collected by the Chandra and XMM-Newton x-ray observatories, researchers have been able to determine the speed of rotation of RX J1131–1231, located some 6.1 billion light-years away. Because the black hole appears to be spinning almost 87% of the maximum possible speed allowed by general relativity, it was probably created by mergers with other black holes rather than by the slow accretion of gas. Such observations add to our knowledge about black holes and help us better understand how they were formed.
