DENVER – Last week, the Horizon Event Telescope (EHT) released the first image of the shadow of a black hole projected against the hot gas of its accretion disk. That image, of the black hole in the center of the Messier 87 galaxy (M87), was front-page news around the world. Soon, the EHT will produce the first film of that hot gas whirling chaotically around the shadow, said the project leaders who spoke on Sunday (April 14) here at the April meeting of the American Physical Society.
The EHT is not a single telescope. Rather, it is a network of radio telescopes around the world that makes synchronized recordings of radio waves accurately, and these recordings can be combined so that different telescopes act as one. As more individual telescopes join the EHT and the team updates the project's recording technology, the detail of the images should increase dramatically, said Shep Doeleman, the astronomer at Harvard University who led the EHT project in his speech. And then, the team should be able to produce black hole movies in action, he said.
"It turns out that even now, with what we have, we may be able, with certain previous badumptions, to observe the signatures of rotation. [evidence of the accretion disk swirling around the event horizon]"Doeleman said." And then, if we had many more stations, we could really start watching movies in real time from the accumulation and rotation of the black hole. " [9 Ideas About Black Holes That Will Blow Your Mind]
In the case of the black hole in M87, Doeleman told Live Science after his talk, making a movie will be quite simple. The black hole is huge, even for a supermbadive black hole in the center of a galaxy: it is 6.5 billion times the mbad of the Earth's sun, with its event horizon, the point beyond which light can not return , enclosing a sphere as wide as Our entire solar system. Therefore, the hot matter of the accretion disk of this black hole takes a long time to make a single walk around the object.
"The time scale on which [M87] Changes appreciably is greater than a day. That's great, "said Doeleman, because it means that the EHT shoots a film of the object frame by frame.
"We can … make our image, then if we want to make another, or a time-lapse movie, then we go out the next day or next week, and we could do it seven weeks in a row and get seven frames of a movie and then I see that something moves that way, "he said.
But the M87 black hole is not the only supermbadive black hole that the EHT is observing. The team is also looking at Sagittarius A *, the supermbadive black hole at the center of our own galaxy, and plans to launch the first image of that object soon. And the EHT researchers also aim to make films from a much closer and better studied black hole, but that project will be more complicated, Doeleman said. [11 Fascinating Facts About Our Milky Way Galaxy]
SagA * is about 1,000 times less mbadive than the M87 black hole, Doeleman said, so the image changes 1,000 times faster.
"So, what it means is that it will change in minutes or hours," Doeleman said. "You have to develop a fundamentally different algorithm, because it's like you have the lens cap off of your camera and something is moving while you're taking an exposure."
To make a movie, he said, the EHT would not only have to collect all the data needed to produce a black hole image, but also split that data into different parts at times. Next, the team would compare those pieces to each other using sophisticated algorithms to discover how the image changed even when it was being captured.
"We have to find a way to see the first part of the data, and then the second part of the data, and then make a movie," he said. "So, the members of our team are working on what we call dynamic images."
This approach uses models of how the image would be expected to move, comparing those models with the actual data to see if it fits.
"You have to be smart and discover how the data from this time segment relates to that time segment," said Doeleman. "So, for example, you can say: OK, you can move but you can not go that far."
By using such restrictions, he said, the team can convert even very limited amounts of data from any minute into complete images of SagA * in motion. As a result, the team hopes to make smaller black hole movies in a single night.
Those films, said Avery Broderick, an astrophysicist at the University of Waterloo in Canada who works on the interpretation of EHT images, should reveal new details about the behavior of accretion discs around black holes, including the way in which they eat the stuff.
"We can make a map of space times by looking at the cinema of black holes, not the portrait," said Broderick.
Originally published in Living science.