Astronomers have revealed the first image of a supermassive black hole in the center of the Milky Way – the Earth’s galaxy. Known as Sagittarius A * (Sagittarius A star), the object is four million times the mass of the Earth’s Sun.
The image – produced by the global team known as the Event Horizon Telescope Collaboration – is the first, direct visual confirmation of this invisible object and comes three years after the first image of a black hole from a distant galaxy.
“It is very exciting for ESO (European Southern Observatory) to have played such an important role in solving the mysteries of black holes and in particular Sgr A * for so many years,” said Xavier Barcons, Director General of the European Southern Observatory. in a release. The results are published in The Astrophysical Journal Letters.
Black holes are areas in space where the pull of gravity is so intense that nothing, including light, can escape.
NASA explained: “The outer edge of a black hole, called its event horizon, defines the spherical boundary where the velocity required to escape exceeds the speed of light. Dust and radiation fall in, but they cannot escape. Because not even light can escape, is a black hole literally black. “
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As a result, the image does not show the black hole itself, which is completely dark, but the glowing gas that surrounds it – four million times more massive than the Sun – in a ring of bent light.
Michael Johnson, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, called Sagittarius A * “swallowing but ineffective” and ate relatively little substance.
“If Sgr A * were a person, it would consume a single grain of rice every million years,” Johnson said Reuters.
Sagittarius A * – abbreviated to Sgr A * and pronounced sadge-ay-star – gets its name from detection in the direction of the constellation Sagittarius.
Scientists have assumed its existence since 1974 after the discovery of an unusual radio source in the center of the galaxy. Astronomers in the 1990s mapped the orbits of the brightest stars near the center of the Milky Way, confirming the presence of a supermassive compact object.
Although the presence of a black hole was considered to be the only plausible explanation, the new image provides the first direct visual evidence. The black hole is 27,000 light-years from Earth.
The image was taken by connecting eight giant radio observatories across the Earth to form a single “earth-sized” virtual telescope – the Event Horizon Telescope.
The Event Horizon telescope stared at Sagittarius A * for several nights for several hours in a row – similar to long-exposure photography. The same process was used to produce the first image of a black hole (M87 *), released in 2019.
Event Horizon Telescope researcher Chi-kwan Chan from the Steward Observatory and the Department of Astronomy and the Data Science Institute at the University of Arizona told Reuters: “The gas near the black holes moves at the same speed – almost as fast as light – around both Sgr A * and M87 *.”
“But where gas takes days to weeks to orbit the larger M87 *, in the much smaller Sgr A * it completes a cycle in minutes. This means that the brightness and pattern of the gas around Sgr A * changed rapidly, while EHT Collaboration observed it – a bit like trying to take a clear picture of a puppy quickly chasing its tail. “
Researchers are happy to get pictures of two black holes in different sizes that allow them to understand how they are compared. They have also started using the new data to test theories about how gas behaves around supermassive black holes.
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Event Horizon Telescope researcher Keiichi Asada of the Department of Astronomy and Astrophysics, Academia Sinica, Taipei, said: “Now we can study the differences between these two supermassive black holes to get valuable new clues as to how this important process works.”
“We have images of two black holes – one at the large end and one at the small end of supermassive black holes in the universe – so we can go much further in testing how gravity behaves in these extreme environments than ever before.”