Researchers gathered under the project Event Horizon Telescope, present Wednesday 10th April, 2019 the result of a cross-observation to capture the image of a black hole.
The end of suspense is approaching: astronomers from around the world, gathered under the project Event Horizon Telescope , present Wednesday, April 10, 2019 the result of a cross-observation to capture the image of a black hole , a first in history of astronomy.
Black holes have been theorised, modelled, detected but never observed. So everyone wonders: how is the photo of a black hole?
According to the law of general relativity published in 1915 by Albert Einstein, who theorises their functioning, the gravitational attraction exerted by these monsters is such that nothing can escape, neither the matter nor the light, whatever the wave length. Result: they are invisible.
An event horizon is an empty shadow. Event Horizon Telescope looks for hot material thrown around by the black hole to see the shadow in contrast. The more active the black hole, the more dramatic the scene. Simulation from EHT. Tomorrow, the real thing. Woa. pic.twitter.com/UWDtDiXPQu
— Janna Levin (@JannaLevin) April 9, 2019
“A photo is the definitive proof”
To circumvent this major handicap, astronomers seek to observe the monster by contrast, on the matter that surrounds it.
In April 2017, eight telescopes around the world had simultaneously targeted two black holes with one goal: to try to get an image. For two years, the scientific community has been waiting for the result.
“A photo is the definitive proof of the existence of black holes,” enthuses Jean-Pierre Luminet, astrophysicist at the French CNRS, author of the first digital simulation of a black hole in 1979. “Even in the scientific community, there is still a lot of resistance, “adds the scientist who wanted at the time” to show the black hole “.
The results of the Horizon Telescope Event will be presented at 3pm at six major press conferences held simultaneously in several cities around the world: Brussels, Santiago, Shanghai, Tokyo, Taiwan and Washington.
Of the 11 observatories planned for the Event Horizon Telescope array, 8 participated in #EHTblackhole observations in 2017. Here is a collage (with older photos!) from the #NSFfunded animation made at @saoastro, to be found on our Youtube channel — https://t.co/U37EF3IlTI. pic.twitter.com/9UUrynnmvD
— Event Horizon ‘Scope (@ehtelescope) April 8, 2019
4.1 million times the sun
By combining eight telescopes across the globe, the EHT has managed to create a virtual telescope of about 10,000 km in diameter , close to the size of the earth.
With the 30-meter IRAM telescope in Europe (managed by the French CNRS, the Max-Planck-Gesellschaft in Germany and the Spanish IGN), the powerful ALMA radio telescope built in Chile (co-managed by Europe, United States and Japan) but also structures in the United States, Hawaii and Antarctica, the Event Horizon Telescope covers a large part of the globe.
The larger the telescope, the more detail it can see. And astronomers have retained two targets: the two black holes, seen from the Earth, are the largest.
One, Sagittarius A * is nestled in the center of the Milky Way, 26,000 light-years away from Earth. Its mass 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 massive black holes, 1500 times more than Sagittarius A *. It has no name and is located 50 million light-years from Earth, in the heart of the M87 galaxy.
It is much bigger than Sagittarius A * but it is so far away from us that, seen from the Earth, “its apparent size should be slightly lower than that” of the first, says the Event Horizon Telescope.
By their observations, astronomers seek to identify the immediate environment of a black hole. According to the theory, when matter is absorbed by the monster, it emits a light. The EHT project, capable of capturing millimeter waves emitted by the environment of the black hole, aims to define the perimeter of the celestial object.
Video. The press conference to follow live: