A historic image shows photographic evidence of a black hole at the center of the Milky Way galaxy
CHICAGO (CBS/AP) — Astronomers on Thursday unveiled the first photographic evidence of a supermassive black hole in the center of the Milky Way.
The image was produced by the Event Horizon Telescope Collaboration, using a network of radio telescopes around the world – including the University of Chicago-affiliated South Pole Telescope, the U of C said. .
The black hole – known as Sagittarius A* – sits at the very center of the galaxy and is so dark you can’t see it. But the ring of light is a telltale sign.
CBS 2’s Jim Williams spoke about the discovery of the black hole with John E. Carlstrom, Subramanyan Chandrasekhar Distinguished Service Professor in the Departments of Astronomy and Astrophysics and Physics at the U of C, who leads the telescope team from the south pole
“I think it’s just great. It’s a major achievement. It’s an achievement that’s stood for over 50 years,” Carlstrom said.
The discovery may also provide clues about the universe, Carlstrom explained.
“We find that black holes are at the center of every major—every galaxy has a black hole. The evidence shows that. we have one in our own backyard – in our own galaxy – and we can zoom in and really look.”
Williams asked Carlstrom to explain, in simple terms, how a black hole shapes our universe.
“I would say our universe shapes black holes,” Carlstrom said. “They’re part of what evolves in our universe – we don’t quite understand that. They’re part of what anchors the galaxies, and of course the galaxies and the stars within them are what give birth to us, and the life. So they’re part of the picture.”
Getting a good picture of Sagittarius A* was a challenge; previous efforts have found the black hole too jittery.
“It was gurgling and gurgling as we watched it,” said Feryal Ozel of the University of Arizona.
The black hole is about 27,000 light-years from Earth and appears to be the same size in the sky as a donut on the moon, the U of C said.
But the real size of the black hole is 4 million times larger than that of the sun.
Ozel described it as a “gentle giant” while announcing the breakthrough along with other astronomers involved in the project. The image also confirms Albert Einstein’s general theory of relativity: the black hole is precisely the size that Einstein’s equations dictate. That’s about the size of Mercury’s orbit around our sun.
Black holes gobble up galactic matter, but Ozel said this one “eats very little.” That’s the equivalent of a person eating a single grain of rice for millions of years, another astronomer said.
Scientists expected the Milky Way’s black hole to be more violent, especially since the only other image from another galaxy shows a much larger and more active black hole.
“It’s the cowardly lion of black holes,” said project scientist Geoffrey C. Bower of Taiwan’s Institute of Astronomy and Astrophysics Academia Sinica.
Because the black hole is “on a starvation diet,” so little matter falls into the center, allowing astronomers to look deeper, Bower said.
The complete results of the study of black holes are available in a special issue of The Astrophysical Journal of Lettersreleased Thursday.