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Mbadive, greedy, overpowering. Predicted by theory but never directly observed, the black holes, of which we could see the first image today, remain among the most enigmatic objects of our cosmos.
A black hole is a celestial object that has an extremely large mbad in a very small volume. As if the Earth was squeezed into a thimble, or the sun was only 6 km in diameter, explained recently Guy Perrin, astronomer at the Observatory of Paris-PSL.
According to the law of general relativity established in 1915 by Albert Einstein, which explains their functioning, the gravitational attraction of these "monsters" is such that nothing can escape, neither matter nor light, whatever the wavelength. We can not therefore directly observe them. In addition, the force of gravity emanating from the black hole is so phenomenal that we do not know how to recreate such an environment in the laboratory.
The two black holes hunted by the researchers of the Event Horizon Telescope collaboration, which must reveal the results of their research today, are two supermbadifs. One, Sagittarius A * is nestled in the center of the Milky Way, 26,000 light years from Earth. Its mbad is equivalent to 4.1 million times that of the Sun. Its radius is one tenth of the distance between the Earth and the Sun. The other is one of the most mbadive known black holes, 6 billion times more than our Sun and 1,500 times more than Sgr A *. It is located 50 million light-years from Earth, in the heart of the M87 galaxy. It is much bigger than Sagittarius A *.
Under the effect of the enormous gravitational attraction, the too close stars are flattened, stretched and then dislocated, the gas brought to extreme heat. Gas and pieces of stars spiral around the black hole to finally plunge, generating a burst of bright ultraviolet light.
"When a black hole starts to suck up the mbad, it becomes very hot, it shines and emits light," says Paul McNamara, scientific officer at ESA (European Space Agency) of LISA Pathfinder, a future space observatory. . Failing to observe a black hole, astronomers have been searching for years to identify the perimeter of a monster through these phenomena taking place in limit.
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