EFE – The first image of the black hole – a space from which nothing, not even light, can escape – at the center of our Milky Way galaxy was unveiled this Thursday by scientists at the Event Horizon Telescope (EHT).
In several simultaneous press conferences held in different countries, researchers showed the historic photograph of this supermassive black hole, called Sagittarius A*; it shows a not perfectly spherical yellow and orange ring, with three brighter spots.
“It is fascinating, really new and extraordinary,” summarized the director-general of the European Southern Observatory (ESO), the Spaniard Xavier Barcons, at the press conference organized by this organization at its headquarters in Garching, near Munich (Germany).
This result constitutes “overwhelming evidence” that the object is indeed a black hole and provides valuable clues about the functioning of these giants, which are believed to reside at the center of most galaxies.
The image has been obtained by a global research team, the Event Horizon Telescope Collaboration, using observations with a worldwide network of eight radio telescopes, which functions as a virtual telescope the size of Earth.
The EHT team’s results are published today in a special issue of The Astrophysical Journal Letters.
A breakthrough photo
The long-awaited image shows “at last what the huge object at the center of our galaxy really looks like,” says ESO.
Previously, the scientific community had already observed stars orbiting around something invisible, compact, and very massive at the center of the Milky Way.
These orbits allowed postulation that this object – known as Sagittarius A* – was a black hole, and today’s image provides the first direct visual evidence of this, say the scientists.
Although we cannot see the black hole itself, because it is completely dark, the bright gas surrounding it has a telltale signature: a dark central region (called a “shadow”) surrounded by a bright ring-shaped structure.
Einstein predicted this years ago
The new image captures light bent by the gravitational force of the black hole, whose mass is four million times that of our Sun.
“What is surprising is how well the size of the ring matches the predictions of Einstein’s theory of general relativity,” said EHT project scientist Geoffrey Bower of the Institute of Astronomy and Astrophysics at the Academia Sinica in Taipei.
“Previous studies, awarded the Nobel Prize in Physics in 2020, had shown that at the center of our galaxy resides an extremely compact object with a mass four million times larger than our Sun,” according to José Luis Gómez, member of the EHT Scientific Council and leader of the EHT group at the Instituto de Astrofísica de Andalucía (IAA-CSIC).
“Now, thanks to the EHT, we have been able to obtain the first visual confirmation that this object is almost certainly a black hole with properties that agree perfectly with Einstein’s Theory of General Relativity,” he says.
The historic image unveiled today is in addition to the one published just over three years ago by the same international team of scientists of a supermassive black hole – eight times the size of the Solar System – but in that case, the object was outside the Milky Way, in the center of another galaxy (Messier 87).
A black hole is a place in space from which nothing can escape, not even light. The force of its gravity is so strong that not even light can escape its pull, and if light, which is the fastest traveling thing in our universe cannot get out, then nothing can.
Albert Einstein formulated the theory that predicts them, although he never understood or accepted them, Karl Schwarzschild was the first to find a solution to Einstein’s equations (although he died before this was understood), and Stephen Hawking described, among others, their properties.
