European Southern Observatory/EHT collaboration
The supermassive Sagittarius black hole at the center of our galaxy has been found to be rotating, dragging space-time with it.
Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news of fascinating discoveries, scientific advances and more.
CNN
—
A new study has found that the supermassive black hole at the center of our galaxy, Sagittarius A*, is rapidly rotating and shifting spacetime around it.
Space-time is a four-dimensional continuum that describes how we see space, fusing one-dimensional time and three-dimensional space together to represent the fabric of space that bends in response to massive celestial bodies.
A team of physicists observed the existing black hole 26,000 light years from Earthwith NASA Chandra X-ray ObservatoryIt is a telescope designed to detect X-ray emissions coming from hot regions in the universe. They calculated the rotation speed of Sagittarius A* using what is known as the outflow method, which looks at radio waves and X-ray emissions that can be found in the material and gases surrounding black holes, known as the accretion disk, according to the study Published October 21 in Monthly Notices of the Royal Astronomical Society.
The researchers confirmed that the black hole is rotating, which causes what is known as the Lens-Thiring effect. Also known as frame drag, this is what happens when a black hole drags on spacetime as it spins. said lead study author Ruth Dalya physics professor at Pennsylvania State University who designed Flow method More than a decade ago.
Since inventing the outflow method, Daly has worked on determining the spins of various black holes and has written a book 2019 study Which has explored more than 750 supermassive black holes.
“With this rotation, Sagittarius A* will dramatically change the shape of the spacetime in its surroundings,” Daly said. “We’re used to thinking and living in a world where all the spatial dimensions are equivalent — the distance to the ceiling, the distance to the wall, the distance to the floor… they’re all kind of linear, and it’s not as if one of them is completely crushed compared to the others.
“But if you have a rapidly rotating black hole, the spacetime around it is asymmetric — the rotating black hole pulls all the spacetime with it…it squashes the spacetime, and it looks kind of like a football,” she said.
Daly said changing space-time is nothing to worry about, but shedding light on this phenomenon could be very useful for astronomers.
“It’s a great tool for understanding the role that black holes play in the formation and evolution of galaxies,” she said. “The fact that they are dynamic entities that can rotate… and then can affect the galaxy they are located in — it’s very exciting and very interesting.”
The rotation of a black hole is given a value from 0 to 1, where 0 means that the black hole does not rotate, and 1 is the maximum spin value. Previously, there was no consensus on the value of Sagittarius A*’s rotation, Daly said.
Daly said that using the outflow method, which is the only method that uses information from the outflow and from material near the black hole, Sagittarius A* was found to have a spin angular momentum value between 0.84 and 0.96, while the spin angular momentum value ranges between 0.84 and 0.96. Between 0.84 and 0.96. M87* – Black hole in Virgo galaxy group 55 million light-years from Earth, it was found to have an orbit of 1 (with a greater uncertainty of plus or minus 0.2) which is close to its mass limit.
While the team found that the two black holes rotate at similar rates, M87* is much larger than Sagittarius A*, Daly said, so Sagittarius A* has less distance to cover and rotates more times per single rotation than M87*.
Daly explained that Sagittarius A* “is rotating much faster (in comparison), not because it has higher rotational angular momentum, but because it has less distance to travel when it rotates once.”
Black holes and galactic history
Daly said that knowing the black hole’s mass and rotation helps astronomers understand how the black hole forms and evolves.
Black holes formed as a result of the merger of smaller black holes usually have a low spin value. Dejan Stojkovic said, a professor of cosmology at the University of Buffalo who was not involved in the study. However, a black hole formed by the accretion of gas surrounding it will experience a high spin value.
The rate at which Sagittarius A* rotates suggests that a significant portion of the black hole’s mass came from accretion, he said.
“The question of whether or not the central black hole in our galaxy is rotating, or how fast it is rotating, is very important,” Stojkovic said in an email.
“Ultimately, we want to measure the properties of the center of our galaxy as best as possible. This way we can learn about the history and structure of our galaxy, test our theories, or even infer the existence of some very interesting objects such as wormholes,” added Stojkovic, who was the lead author of the book. 2019 study On virtual structures.
“Infuriatingly humble alcohol fanatic. Unapologetic beer practitioner. Analyst.”