Messier 87 is a giant elliptical galaxy located some 53 million light-years away in the constellation of Virgo. In April 2019, astronomers from the Event Horizon Telescope (EHT) Collaboration released stunning images of M87*, the supermassive black hole in the center of Messier 87. M87* is known to have an accretion disk, which feeds matter into the black hole, and a relativistic jet. Now, M87* has yielded another first: the jet shooting out from the black hole has been confirmed to wobble, providing direct proof that M87* is spinning.
“Supermassive black holes, monsters up to billions of times heavier than the Sun that eat everything around them including light, are difficult to study because no information can escape from within,” said Dr. Yuzhu Cui, an astronomer at the Zhejiang Laboratory and the National Astronomical Observatory of Japan (NAOJ), and colleagues.
“Theoretically, there are very few properties that we can even hope to measure.”
“One property that might possibly be observed is spin, but due to the difficulties involved there have been no direct observations of black hole spin.”
In the study, the astronomers accurately traced the long-term evolution of the jet near M87*.
They analyzed 170 very long baseline interferometry images of the jet obtained with the East Asian VLBI Network (EAVN) and the Very Long Baseline Array (VLBA) between 2000 and 2022.
Their results show that gravitational interactions between the accretion disk and the black hole’s spin cause the base of the jet to wobble, or precess, much the same way that gravitational interactions within the Solar System cause the Earth to precess.
The authors successfully linked the dynamics of the jet with the central supermassive black hole, providing direct evidence that the black hole does in fact spin.
The jet’s direction changes by about 10 degrees with a precession period of 11 years, matching theoretical supercomputer simulations.
“We are thrilled by this…
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