8/16/2023 0 Comments First black hole image![]() From our perspective here on Earth, active galactic nuclei are a thing of the past-we see them only in the distant, ancient universe. Scientists started to suspect that a black hole lurked in the heart of the Milky Way in the early 1960s, not long after the discovery of active galactic nuclei-extremely bright regions at the cores of some faraway galaxies illuminated by voraciously feeding supermassive black holes. Now, at last, they've gained the ability to watch it evolve-to watch as it feeds on flaring, flashing streams of matter-in real time. Through decades of study with all manner of telescopes, astronomers already knew Sagittarius A*'s basic measurements (its mass, diameter and distance from Earth) to great accuracy. ![]() If Sagittarius A*'s mercurial nature made it hard to see, it also makes it an ideal laboratory for understanding black holes and Einstein's general theory of relativity, his hallowed theory of gravity. Katie Bouman, a California Institute of Technology computer scientist and astronomer who co-leads the EHT's imaging working group, said that matter orbits Sagittarius A* so quickly that it changes “minute to minute.” Imagine taking a time-lapse photograph of a speeding bullet-it's not easy. Sagittarius A* is more than 1,000 times less massive, so its appearance changes about 1,000 times faster, as matter moves in tighter, quicker orbits around the black hole. Practically speaking, that means you can stare at it for a long time, and it will scarcely change. The observatory's previous target, M87*, the black hole at the heart of the galaxy Messier 87 (M87), is so huge that the matter swirling around it takes many hours to complete a full orbit. But the bigger challenge was that Sagittarius A* is constantly changing. Part of the reason it took so long was the global devastation of the COVID pandemic. The scientists then spent years analyzing the raw data and converting them into an image. In April 2017 the EHT collaboration spent several nights pointing that virtual instrument at Sagittarius A* and other supermassive black holes. The EHT captured images of this shadow using a technique called very long baseline interferometry (VLBI), which combines radio observatories on multiple continents to form a virtual Earth-size telescope, an instrument with the highest resolution in all of astronomy. But they warp spacetime around them so severely that, when they are illuminated by glowing streams of infalling matter shredded in their gravitational grip, they cast a “shadow.” The shadow is about two and a half times larger than a black hole's event horizon, the boundary in spacetime through which nothing that passes can ever return. Sagittarius A* is our own private supermassive black hole, the still point around which our galaxy revolves.īlack holes trap everything that falls in, including light, so they are, in a very real sense, unseeable. It wasn't the first picture of a black hole this collaboration had captured-that was the iconic image of M87*, which they revealed in April 2019. This past spring, however, the astronomers behind the Event Horizon Telescope (EHT) settled the matter by unveiling the first image of a supermassive black hole at the center of the Milky Way. For example, when astronomers Reinhard Genzel and Andrea Ghez shared a portion of the 2020 Nobel Prize in Physics, their citation specified that they were awarded for “the discovery of a supermassive compact object at the centre of our galaxy,” not the revelation of a “black hole.” The object is known as Sagittarius A* (“Sagittarius A star”). Scientists have long thought that only a supermassive black hole could explain the stars' movements, but until this year, they hesitated to say that outright. This is a place where stars slingshot around apparently empty space at an appreciable fraction of the speed of light. ![]() The AP is solely responsible for all content.Deep in the heart of the Milky Way, strange things happen. Things are calm out here.”įollow Seth Borenstein on Twitter at Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. “We live out in the suburbs (in a spiral arm of the galaxy). Things move fast,” Ghez said in an interview. It’s “like an urban downtown, everything is more extreme. National Science Foundation.Įven though it is quieter than expected, the center of the Milky Way is an important place to study, Ghez said. The project cost nearly $60 million with $28 million coming from the U.S. The next step is a movie of one of those two black holes, maybe both, Fish said. To get the picture, the eight telescopes had to coordinate so closely “in a process similar to everyone shaking hands with everyone else in the room,” said astronomer Vincent Fish of the Massachusetts Institute of Technology.Īstronomers worked with data collected in 2017 to get the new images.
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