The first photo of this cosmic monster tapi at the heart of our galaxy was obtained from a long data processing collected in 2017 by an international observatoric consortium.
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Like a unmasked spy, the one who was just a code name – Sagittarius has* – now has a “face”. Thursday, May 12, the scientific consortium event horizon telescope (eht), which brings together more than 300 researchers around the world, has, in fact, revealed the photo of a very discreet, even invisible, character, the giant black hole which sits in the center of our galaxy, the Milky Way. In the image, the funny face is a bit vague: an orange disc with lighter, almost white areas, and, in the middle, a dark spot. This shadow is Sagittarius a*, which takes its name from the constellation of the sagittarius of which it is the most brilliant source in radio waves (hence the A, the first letter of the alphabet). By definition, a black hole is a body so dense that its gravitational field brings everything back to it, including light that cannot escape it. On a shot, we can therefore only “see” it in Chinese shadows, by contrast on a light background, that of the gas and dust disc which, gravitating around it at a crazy speed, is heated white.
Let us recognize it, the image looks like already. In April 2019, the same consortium had already caused a sensation by publishing the first photo of a black hole, that of the M87 galaxy. Same light ring, same dark puddle in the center. “The result is perhaps a little disappointing because the two images are very similar, concedes Frédéric Gueth, deputy director of the Institute of Millimetric Radioastronomy (IRAM), an organization founded by the CNRS and the Max-Planck Institute for the ‘Astronomy which is part of the EHT. But, in reality, it is a very interesting result which shows two things. First of all, it is a confirmation of the first observation, which was not due to a Hidden error went unnoticed. “
Einstein predictions verified by observation
“Second, continues Frédéric Gueth, it must be taken into consideration that the masses of these two objects are very different: in the case of Sagittarius A*, we have a black hole of a few million times the mass of the sun, then that that of M87 is a monster of several billion times the mass of the sun. And yet, they have roughly the same head. This is exactly what general relativity forecasts. “This one says that it happens Always the same thing just outside a black hole, whatever its mass (and its size, which is proportional to it). “The goal of the game was to answer the question: is there a difference between what is observed and the predictions of theory? And the answer, at present, is … no”, concludes the director IRAM assistant. Geoffrey Bower, EHT scientific manager, said: “We were amazed to see how the size of the ring was the predictions of the theory of general relativity of Einstein.” Albert can therefore rest quietly.
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