This is the first time such an effect, known as precession, has been seen in black holes, where the twisting is 10 billion times faster than in previous observations.
This artist’s conception shows two supermassive black holes, similar to those observed by Bansal et al, orbiting one another more than 750 million light years from Earth. Image credit: Josh Valenzuela, University of New Mexico.
The binary black hole in question was detected through the gravitational-wave event GW200129 on January 29, 2020, by the three-detector LIGO-Virgo network.
One of the black holes, 40 times bigger than our Sun, is likely the fastest spinning black hole to be found through gravitational waves.
And unlike all previous observations, the rapidly revolving black hole distorted space and time so much that the binary’s entire orbit wobbled back and forth. This form of precession is specific to Einstein’s theory of general relativity.
These results confirm its existence in the most extreme physical event we can observe, the collision of two black holes.
“We’ve always thought that binary black holes can do this,” said lead author Professor Mark Hannam, a researcher with the Gravity Exploration Institute at Cardiff University.
“We have been hoping to spot an example ever since the first gravitational wave detections. We had to wait for five years and over 80 separate detections, but finally we have one!”
A more down-to-earth example of precession is the wobbling of a spinning top, which may wobble — or precess — once every few seconds. By contrast, precession in general relativity is usually such a weak effect that it is imperceptible.
In the fastest example previously measured from orbiting neutron stars called binary pulsars, it took over 75 years for the orbit to precess.
The GW200129 black-hole binary precesses several times every second — an effect 10 billion times stronger than measured previously.
“It’s a very tricky effect to identify,” said co-author Dr. Jonathan Thompson, also from the Gravity Exploration Institute at Cardiff University.
“Gravitational waves are extremely weak and to detect them requires the most sensitive measurement apparatus in history.”
“The precession is an even weaker effect buried inside the already weak signal, so we had to do a careful analysis to uncover it.”
The findings were published in the journal Nature.
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M. Hannam et al. General-relativistic precession in a black-hole binary. Nature, published online October 12, 2022; doi: 10.1038/s41586-022-05212-z
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