Astronomers have finally spotted the center of the Milky Way galaxy, unmasking a giant black hole, a celestial vortex 26,000 light-years from Earth that should otherwise be hidden from view.
An international team of researchers released a snapshot of the supermassive black hole known as Sagittarius A* on Thursday., spied on through the power of eight linked radio antennas from around the world that together can penetrate through the gas clouds in outer space. Although black holes are, by definition, invisible (light can’t travel fast enough to escape their clutches), Sagittarius A* revealed itself as a black shadow surrounded by the brilliant glow of gas and debris falling from it. swirled around its perimeter.
The photo showed a region in deep space reminiscent of a solar eclipse: a dark circle, enveloped in a fluff of radiant red-orange light. The image was colored so that human eyes could perceive it.
Until three years ago, any depiction of a black hole was simply an artist’s rendering or a computer model of what the spinning and bending phenomenon of space-time might look like. This object, seen in the photo at the top of this story, is real, with each pixel representing a herculean effort: hundreds of scientists from 80 institutions around the world, working together to collect, process, and piece together bits of data.
The breakthrough was also published in the scientific journal. Astrophysical journal letters. Spokespeople for the Event Horizon Telescope, the international collaboration of 300 scientists who worked on the feat, held simultaneous news conferences in at least seven countries to share the news, including the United States at the National Press Club in the nation’s capital.
The image of Sagittarius A*, pronounced “Sagittarius A-Star,” is a monumental achievement, the second time scientists have broken through the invisibility barrier to glimpse a black hole. The first photo, revealed in April 2019, showed the black hole residing at the center of the galaxy Messier 87, an easier target to capture due to its size, despite being much further away, some 53 million years away. distance light. Astronomers say the black hole, dubbed M87*, is as big as Earth’s eight-planet solar system.
The second photo provides powerful confirmation to the scientific community, said Feryal Özel, a professor of astronomy and physics at the University of Arizona.
“Now we know it wasn’t a coincidence, it wasn’t some aspect of the environment that looked like the ring we expected to see,” he said at the Washington, DC news event. “Now we know that, in both cases, what we see is the heart of the black hole, the point of no return. These two images look alike because they are the consequence of the fundamental forces of gravity.”
Astronomers see the first supermassive black hole as it grows
This graph shows how much larger the supermassive black hole in the galaxy M87 is than Sagittarius A* (which is at the center of our Milky Way galaxy).
Credit: National Science Foundation / Keyi “Onyx” Li
Sagittarius A*, or Sgr A* for short, it’s considerably smaller, at about 27 million miles across, but it’s not a pipsqueak. Scientists estimate that it is 4 million times more massive than the sun. To make a difficult-to-understand number even more unfathomable, imagine this: the mass of the sun is equal to 333,000 Earths.
Its home in the Milky Way, a spiral galaxy, is quite flat, but the center sinks where the supermassive black hole is located. Around him are stars that slide in various directions. But the hole, often anthropomorphized in pop culture as a space monster, is actually quite “soft,” the researchers say, consuming relatively little of its surroundings.
Black holes are some of the most elusive things in outer space. The most common type, called a stellar black hole, is often thought to be the result of a huge star dying in a supernova explosion. The star’s material then collapses in on itself, condensing into a relatively small area.
But how supermassive black holes, millions to billions of times more massive than the sun, form is even more mysterious than typical stellar black holes. Many astrophysicists and cosmologists believe that these giants lurk at the center of virtually every galaxy. Recent Hubble Space Telescope observations have bolstered the theory that supermassive black holes originate in the dusty cores of starburst galaxies, where new stars are rapidly being produced, but scientists are still ironing out the problem.
Black holes don’t have surfaces, like a planet or a star. Instead, they have a limit called the “event horizon”, it’s a point of no return. If something swoops in too close, it will fall and never escape the hole’s gravitational pull.
Prior to the groundbreaking image on May 12, the Event Horizon Telescope team published the first photo of a black hole in the Messier 87 galaxy in April 2019.
credit: Chip Somodevilla/Getty Images
Yes M87* Offering proof that black holes were not science fiction, Sgr A* is testimony to decades of growing observational science. Before the first photo of the black hole, scientists inferred the presence of a hole in space by detecting its impact on nearby stars and gas. Albert Einstein, whose theory of general relativity predicted black holes more than a century ago, and Stephen Hawking, a cosmologist who spent much of his career proving their existence mathematically, are among the many figures who paved the way for the Thursday reveal.
If M87* offered evidence that black holes were not science fiction, Sgr A* is testimony to decades of growing observational science.
Sgr A* is exciting to scientists because it is ordinary, said Michael Johnson of the Harvard Smithsonian Center for Astrophysics. the central supermassive black hole is representative of many others in the universe, allowing experts to learn more about these mysterious space objects.
Despite their visual similarities — one burning donut versus another burning donut — the two black holes couldn’t be more different, the scientists said. M87* it’s accumulating matter at a significantly faster rate, but the Milky Way’s central black hole changes appearance more quickly: it takes only a few minutes for gas to fully orbit it, while an orbit around its predecessor takes about two weeks.
Furthermore, the first imaged black hole releases a huge jet of radiation that extends to the edge of its galaxy, while Sgr A* does not.
To collect the huge amount of data needed to process the new image, the Event Horizon Telescope used a technique called very long baseline interferometry, which synchronizes observatories around the world and takes advantage of the Earth’s rotation to form a virtual telescope. the size of a planet. . Together, the instruments were able to see the sky with the same view needed to read a newspaper in New York from Paris, according to the organization.
At the time of the 2019 black hole announcement, collaborators with the Event Horizon Telescope said they had also tried to image this supermassive black hole, but the team had been unable to obtain a clear image. As one of the most studied supermassive black holes in the universe, it was a disappointment to many astrophysicists who longed to peer into our galaxy’s own navel.
“For me personally, I met him 20 years ago and loved him and tried to understand him ever since,” Özel said on Thursday.
This time, scientists added the South Pole Telescope, which was not used in the M87* photo, to the suite of virtual telescopes to improve the resolution of their images. The researchers gathered five petabytes of data, about 2.5 billion pages of printed text, to catch even a glimpse of this black hole, said Dom Pesce, a member of the telescope team.
Put another way, that’s the equivalent amount of data in about 100 million TikTok videos, said Vincent Fish, a research scientist at the MIT Haystack Observatory. That’s too much to transmit over the Internet, so scientists had to ship hundreds of hard drives to two centers in western Massachusetts and Bonn, Germany, where supercomputers could process the raw data.
Credit: Daniel Michalik/National Science Foundation
It is true that the photo of Sgr A* is blurred. Johnson likened the blur to looking through frosted glass. Radio waves containing crucial image details are scattered, making the sharp outline of the hole look more like a ring of jelly. To fix that, the telescopes have to be farther apart or reach higher frequencies, he said.
“We don’t think the black hole is actually a blurry image in the sky,” Johnson said. “We’re right at our breaking point here.”
“We don’t think the black hole is actually a blurry image in the sky.”
With financial support from the National Science Foundation and other groups, the scientists plan to improve their technology to make the image much sharper.
Another next step for the collaboration is to try to turn these still images into videos, so scientists can watch gas fall toward the black holes’ event horizons. That project could be completed sometime after 2024, they said.
But just in case anyone is disappointed by another donut on fire, Katie Bouman, an assistant professor of astronomy at Caltech, was reminded of the amount of data that goes into the image.
“This image is actually one of the sharpest images you’ve ever seen,” he said.