Astronomers have unveiled the first sight of a supermassive black hole in the center of the Milky Way – 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 a global team known as Event Horizon Telescope Collaboration – comes three years after the first, direct visual confirmation of this invisible object and the first image of a black hole from a distant galaxy.
Xavier Barkons, director general of the European Southern Observatory, said: “It is very exciting for ESO (European Southern Observatory) to play a key role in unraveling the mystery of the black hole and especially Sgr A * for so many years.” The results have been released in a release Astrophysical Journal Letters.
A black hole is a region of space where the gravitational pull is so strong that nothing can escape, including light.
NASA explains: “The outer edge of a black hole, called the event horizon, defines a spherical boundary where the velocity required to escape exceeds the speed of light. Substances and radiation fall inside, but they cannot escape. Because even light can’t escape, a black hole is literally black. “
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As a result, the image does not depict a black hole, which is completely dark, but the luminous gas that surrounds it – four million times larger than the sun – in a ring of curved light.
Michael Johnson, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, called Sagittarius A * “ironic but incompetent”, eating relatively little food.
“If Sgr A * were a person, it would eat one grain of rice every million years,” Johnson said. Reuters.
Sagittarius A * – abbreviated Sgr A * and pronounced sadge-ay-star – got its name from Sagittarius identification.
Scientists have speculated about its existence since 1974 after discovering an unusual radio source at the center of the galaxy. In the 1990’s, astronomers 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 seemed to be the only plausible explanation, the new image provided the first direct visual evidence. Black holes are 27,000 light-years from Earth.
A single “Earth-sized” virtual telescope – the image was taken by connecting eight giant radio observatories around the world to form the Horizon Telescope.
Event Horizon Telescope Sagittarius looks at the night A * for hours on end – like long-exposure photography. The same process was used to create the first visual of a black hole (M87 *) released in 2019.
Event Horizon Telescope Scientist Chi-Quan Chan reports from the Steward Observatory and the Department of Astronomy and the Data Science Institute at the University of Arizona. Reuters: “The gas around the black hole travels at the same speed – almost as fast as light – close to both Sgr A * and M87 *.”
“But where it takes days to weeks to orbit the larger M87 * of gas, on much smaller Sgr A * it completes an orbit in just a few minutes. It was like watching a puppy quickly chase its tail and take a clear picture. “
Scientists are excited to get pictures of two black holes of different sizes, giving them a chance to understand how they compare. They have begun using new data to test theories on how gases behave around supermassive black holes.
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Event Horizon Telescope scientist Keichi Asada of the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, says: “Now we can study the differences between these two supermassive black holes to gain valuable new clues about how this important process works.”
“We have images of two black holes – one at the large end and one at the small end of the supermassive black hole in the universe – so we can go much further to examine how gravity behaves in this extreme environment.”