The telescope is named after the point of no return around the black hole. The team achieved its first victory in April 2019, when it submitted an image of the M87 black hole. In 2021, team members refined their data to detect magnetic fields orbiting the black hole like a finely grooved gun barrel pumping matter and energy into the vacuum.
The Sagittarius A* data was recorded during the same observational process in 2017 that produced the M87 image, but with more antennas — eight instead of seven — because the team was able to include the South Pole telescope that can’t see M87.
Sagittarius A*, the Milky Way’s black hole, was a more difficult target. It is less than one-thousandth the mass and size of the M87 hole, and therefore it is evolving a thousand times faster. M87’s black hole barely budged during a week-long observation tour, but Sagittarius A* changes its appearance every five minutes, “annoying and gurgling” in the words of Dr. Ozil.
“The main thing is that, for the M87, after a week of observation, it hardly buds,” Dr. Doelman said. He likened it to “Buddha, just sitting there.”
By comparison, he said, the arc black hole was “spinning.” Orbiting around it can take as little as four minutes or half an hour, depending on how it’s spinning. “Even over night observation. It changes as you collect data,” he said. “You try to take a picture of something with the lens hood on and you get this blurry mess.”
Dr. Doeleman’s new goal is to expand the network to include more antennas and get enough coverage to produce a film about the arc black hole. The challenge for black hole cinema will be to separate what remains the same from what changes – to determine the basic structure of a black hole from the matter that orbits in it.
The results could be startling and informative, said Jana Levine, a gravity theorist at Barnard College at Columbia University, who was not part of the project. “I’m not bored yet of images of black holes,” she said.
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