The existence of a gigantic black hole in our galaxy was finally confirmed thanks to a unique cosmic photograph. But the first image, obtained after 5 years and through the concatenation of 8 observatory satellites, does not portray a voracious cosmic destroyer, but rather what astronomers called this Thursday a “gentle giant”, with a diet close to the starvation.
In other words, that monster, located almost around the corner inside our Milky Way, is “swallowing” very little matter compared to usual.
Astronomers believe that almost all galaxies, including our own, have these giant black holes at their bustling, crowded centers, where light and matter cannot escape, making them extremely difficult to image. The light is bent and rotated by gravity as it is sucked into the abyss along with superheated gas and dust.
The colorized image was released Thursday by an international consortium behind the Event Horizon Telescope, a collection of eight synchronized radio telescopes around the world. Getting a good image was a challenge, experts said. Previous efforts found that the black hole was too “jittery.”
“It was bubbling and gurgling as we watched it,” said Feryal Ozel of the University of Arizona, who described the hole as a “gentle giant” while announcing the progress 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 dictated by Einstein’s equations. It is about the size of Mercury’s orbit around our sun.
Black holes gobble up galactic material, but Ozel said the one in our galaxy, dubbed Sagittarius A, is “eating very little.” It’s the equivalent of a person eating a single grain of rice for millions of years, another expert noted.
“Images of black holes are the hardest thing to think about,” added astronomer Andrea Ghez of the University of California. She was not part of the telescope team, but won a Nobel Prize for the discovery of the Milky Way’s black hole in the 1990s.
Ghez pointed out that the image of “my baby” is exactly as it should be: a creepy-looking red-orange ring with pitch blackness in the center.
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 like the cowardly lion of black holes,” said project scientist Geoffrey C. Bower of the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. Because the black hole “is on a starvation diet,” very little material falls into the center, and that allows astronomers to look deeper, he explained.
Sagittarius A is located near the edge of the constellations Sagittarius and Scorpius in the Milky Way and is 4 million times more massive than our sun. Bower said it’s probably more typical of those at the center of most galaxies, “just sitting there doing very little.”
It’s unbelievably hot, trillions of degrees, Ozel added.
The same group of telescopes published the first image of a black hole in 2019. The image was of a galaxy 53 million light-years away that is 1,500 times larger than our own. The Milky Way’s black hole is much closer, some 27,000 light-years away. A light year is 5.9 billion kilometers.
To get an idea, the eight telescopes had to coordinate very 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.
Scientifically there is no lifespan for a phenomenon like this and it is not known what is beyond the hole. That is another mystery to unveil.
