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Scientists were aware there was a huge object hidden at the centre of the Milky Way, and they also knew it had no hair. The EHT collaboration has now obtained the very first image of Sagittarius A*, the supermassive black hole at the heart of our Galaxy.
Until now, the presence of Sagittarius A* (Sgr A*) could only be suspected, either from a few radio emissions or by observing the paths of stars orbiting at high speed around a gigantic yet invisible object. The Event Horizon Telescope (EHT) collaboration and its global array of radio telescopes have now obtained an image of the supermassive black hole lurking at the centre of the Milky Way. This is only the second direct image of this type of object ever obtained, following the EHT collaboration's 2019 release of the first-ever image of a black hole, at the centre of the galaxy M87.
“We can now study the differences between these two supermassive black holes to gain valuable new clues about how this important process works,” says Keiichi Asada, an EHT scientist at the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei (Taiwan). “We have images of two black holes – one at the large end and one at the small end of the supermassive black holes in the Universe – so we can go a lot further in testing how gravity behaves in these extreme environments than ever before.”
The bright accretion disk orbiting around the 4.3 million solar masses of Sgr A* at near-light speeds has a diameter equivalent to 30 times that of the Sun, but since it is located 27,000 light years from Earth it appears to be about the same size in the sky as a doughnut on the Moon. Therefore, to obtain this picture, the researchers had to combine the data collected night after night by the EHT's eight telescopes linked together across the planet, and then refine the ‘raw’ images produced using numerical models of black holes. The EHT team's findings are published on 12 May, 2022 in a special issue of the journal The Astrophysical Journal Letters.
news.cnrs.fr
Until now, the presence of Sagittarius A* (Sgr A*) could only be suspected, either from a few radio emissions or by observing the paths of stars orbiting at high speed around a gigantic yet invisible object. The Event Horizon Telescope (EHT) collaboration and its global array of radio telescopes have now obtained an image of the supermassive black hole lurking at the centre of the Milky Way. This is only the second direct image of this type of object ever obtained, following the EHT collaboration's 2019 release of the first-ever image of a black hole, at the centre of the galaxy M87.
“We can now study the differences between these two supermassive black holes to gain valuable new clues about how this important process works,” says Keiichi Asada, an EHT scientist at the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei (Taiwan). “We have images of two black holes – one at the large end and one at the small end of the supermassive black holes in the Universe – so we can go a lot further in testing how gravity behaves in these extreme environments than ever before.”
The bright accretion disk orbiting around the 4.3 million solar masses of Sgr A* at near-light speeds has a diameter equivalent to 30 times that of the Sun, but since it is located 27,000 light years from Earth it appears to be about the same size in the sky as a doughnut on the Moon. Therefore, to obtain this picture, the researchers had to combine the data collected night after night by the EHT's eight telescopes linked together across the planet, and then refine the ‘raw’ images produced using numerical models of black holes. The EHT team's findings are published on 12 May, 2022 in a special issue of the journal The Astrophysical Journal Letters.
Black hole Sgr A* unmasked
Scientists were aware there was a huge object hidden at the centre of the Milky Way, and they also knew it had no hair. The EHT collaboration has now obtained the very first image of Sagittarius A*, the supermassive black hole at the heart of our Galaxy.
news.cnrs.fr
