The supermassive black hole at the center of our galaxy, Sagittarius A*, is spinning rapidly and altering the space-time around it, a new study has discovered.
Spacetime is the four-dimensional continuum that describes how we see space, merging one-dimensional time and three-dimensional space to represent the fabric of space that curves in response to colossal celestial bodies.
A team of physicists observed the black hole, which is 26,000 light years from Earth, with NASA’s Chandra X-ray Observatory, a telescope designed to detect X-ray emissions from hot regions of the universe. They calculated the rotation speed of Sagittarius A* using what is known as the outflow method, which analyzes radio waves and X-ray emissions that can be found in the material and gases surrounding black holes. also known as an accretion disk, according to the study published on October 21 in Monthly Notices of the Royal Astronomical Society.
Researchers confirmed that the black hole is spinning, generating what is known as the Lense-Thirring effect. Also known as frame dragging, the Lense-Thirring effect is what happens when a black hole drags with spacetime along with its spin, said study lead author Ruth Daly, a professor of physics at Pennsylvania State University, who designed the outflow method more than a decade ago.
Since the invention of the outflow method, Daly has been working to determine the spin of various black holes and authored a 2019 study that explored more than 750 supermassive black holes.
“With this spin, Sagittarius A* will dramatically alter the shape of space-time in its vicinity,” Daly said. “We are used to thinking and living in a world where all spatial dimensions are equivalent: the distance to the ceiling, the distance to the wall and the distance to the floor… they are all linear, it is not as if one is completely squashed in comparison. with the others.
But if you have a rapidly spinning black hole, the space-time around it is not symmetrical: the spinning black hole drags all of space-time with it…it crushes space-time, and in some ways it looks like a ball of football,” he explained.
The disruption of space-time is nothing to worry about, but shedding light on this phenomenon could be very helpful to astronomers, Daly said.
“It’s a wonderful tool for understanding the role black holes play in the formation and evolution of galaxies,” he said. “The fact that they are dynamic entities that can rotate… and then that can impact the galaxy that it’s in, is very exciting and very interesting.”
The spin of a black hole is assigned a value from 0 to 1, where zero means the black hole is not spinning and 1 is the maximum spin value. Previously there was no consensus on the value of the Sagittarius A* spin, Daly said. According to Daly, with the outflow method, which is the only one that uses information from both the outflow and the material in the vicinity of the black hole, the black hole has a spin angular momentum value between 0.84 and 0.96, while M87*, a black hole in the Virgo galaxy cluster located 55 million light years from Earth, has a spin value of 1 (with an uncertainty greater than plus or minus 0.2) and is close to the maximum for its mass.
While the team had discovered that the two black holes were spinning at similar speeds, M87* is much more massive than Sagittarius A*, so Sagittarius A* has less distance to travel and spins more times for each spin of M87*.
Sagittarius A* “spins much faster (in comparison), not because it has a higher spin angular momentum, but because it has less distance to travel when it spins,” Daly explained.
Knowing the mass and spin of a black hole helps astronomers understand how it might form and evolve, Daly said. Black holes that formed as a result of the merger of smaller black holes would typically have a low spin value, he added. However, the speed at which Sagittarius A* is spinning would indicate that a significant portion of the black hole’s mass comes from accretion.
“The question of whether or not our central galactic black hole is spinning, or at what speed it is spinning, is quite important,” said Dejan Stojkovic, a professor of cosmology at the University at Buffalo, who was not involved in the study. “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 and intriguing objects like wormholes,” he added.
With the discovery that Sagittarius A* is spinning, astronomers are unlocking new information to understand the role that black holes play in the formation and evolution of galaxies.