Astronomers Measure Spin Of A Black Hole

Posted: Jan 13 2019, 4:03am CST | by , in Latest Science News


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Astronomers Measure Spin of a Black Hole
This artist's impression shows an X-ray-bright region in the disk around a black hole, which allows the spin of the black hole to be estimated. Credit: NASA/CXC/M. Weiss

Data from multiple telescopes suggests that the black hole in ASASSN-14li is spinning at about 50 percent the speed of light.

When a star comes too close to a black hole, the intense gravity of the black hole rips apart the passing object. This process of destruction is known as a tidal disruption event. During such events, stellar debris or the material pulled from the doomed star forms a rotating disk around the black hole and emits intense X-rays.

On Nov. 22, 2014, researchers observed a tidal disruption event in a galaxy that lies nearly 300 million light years from Earth. They tracked the event with multiple telescopes, including European Space Agency's XMM-Newton space observatory and NASA‘s Chandra and Swift. When researchers looked through data, they found an intense periodic pulse or signal of X-rays across all datasets. The stable signal appears to have originated from an area very close to the black hole's event horizon or the innermost orbit (ISCO). It brightened and dimmed every 131 seconds for over 450 days. The signal in recent tidal disruption, named ASASSN-14li, gave researchers an idea of how fast the black hole was spinning. They calculated that the black hole is spinning about half the speed of light.

"That's not super fast – there are other black holes with spins estimated to be near 99 percent the speed of light. But this is the first time we're able to use tidal disruption flares to constrain the spins of supermassive black holes." Lead author Dheeraj Pasham from MIT's Kavli Institute for Astrophysics and Space Research said.

Based on latest results, researchers suggest that such tidal disruption event can be used to estimate the spin of a black hole that is otherwise a difficult task.

"Events where black holes shred stars that come too close to them could help us map out the spins of several supermassive black holes that are dormant and otherwise hidden at the centers of galaxies," said Pasham. “This could ultimately help us understand how galaxies evolved over cosmic time."

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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