Astronomers have made the first reliable measurement of a monster black hole’s spin, showcasing a technique that could help unravel the mysteries of these monsters’ growth and evolution.
The enormous black hole at the center of the spiral galaxy NGC 1365 is spinning about 84 percent as fast as Einstein’s general theory of relativity allows it to, researchers determined. “It’s the first time that we can really say that black holes are spinning,” study co-author Fiona Harrison, of Caltech in Pasadena, told SPACE.com. “The promise that this holds for being able to understand how black holes grow is, I think, the major implication.”
Staring at a black hole in X-ray light
Supermassive black holes are almost incomprehensibly huge, with some containing 10 billion or more times the mass of our sun. Scientists think one lurks at the heart of most, if not all, galaxies. NGC 1365, located about 56 million light-years from Earth in the constellation Fornax, does indeed harbor a gigantic black hole — and it is blasting out enormous quantities of energy as it gobbles up gas and other nearby matter, making it an intriguing target for astronomers.
In the new study, researchers analyzed observations two X-ray space telescopes — the European Space Agency’s XMM-Newton observatory and NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR). Astronomers found that the hole’s emissions are strongly distorted, but there is a big controversy over why.
Pinning down a black hole’s spin
The NuSTAR’s super sensitive measurements of high-energy X-rays finally cracked the case.
“To shine through these thick clouds, the black hole would have to be so bright it would basically blow itself apart,” said Harrison, who’s principal investigator for the NuSTAR mission. “So what has to be happening is, what we’re seeing is these relativistic distortions. And that means that the disk is coming close to the black hole, which means the black hole must be spinning rapidly…what you can say is that spinning black holes twist space-time around them. And if you were standing near the black hole, basically your space-time would be twisted, or dragged, around such that you would have to rotate once every four minutes just to be standing still.”
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