First black hole image to be unveiled next Wednesday


First black hole image to be unveiled next Wednesday

(Archive) Illustration of black hole – NASA / ESA / HUBBLE / AFP / Archives

Can we finally see a black hole? An international collaboration of radio telescopes and observatories, the Event Horizon Telescope (EHT) project, which seeks to capture the first image of one of these space "monsters", announces "an unprecedented result" for next Wednesday.

The mystery is all about what will be revealed, but the mobilization is exceptional: "Six major press conferences will be held simultaneously in the world: Belgium (Brussels), Chile (Santiago), China (Shanghai), Japan (Tokyo) Taipei Taiwan) and the United States (Washington), "says the European Southern Observatory (ESO).

In April 2017, eight telescopes in different parts of the world simultaneously pointed to two black holes: Sagittarius A * in the center of the Milky Way and its congener in the center of the M87 galaxy. The goal: try to get an image.

Because although it is spoken of black holes since the century XVIII, no telescope allowed to "see" one.

"We believe that what we call a black hole exists in the universe, even though we have never seen one," Paul McNamara, a scientist in charge of the European Space Agency (ESA) at LISA Pathfinder, told AFP.

Black holes are celestial bodies that have an extremely important mass in a very small volume. As if the Sun were only 6 kilometers in diameter or the Earth was compressed to the size of a finger.

They are so massive that nothing escapes them, neither matter nor light, regardless of their wavelength. The other side of the coin is that they are invisible.

But science is progressing. "The major recent developments are in the field of observation," British astrophysicist Martin Rees, a former partner of Stephen Hawking of Cambridge University, told AFP last month.

– Giant virtual telescope –

The Event Horizon Telescope, when it manages to create an Earth-sized virtual telescope about 10,000 kilometers in diameter, illustrates well the advances in radio astronomy.

With an undeniable differential, because the larger the telescope, the more details it allows to see.

"Instead of building a giant telescope (which would risk sinking under its own weight), several observatories are combined as if they were small fragments of a giant mirror," Michael Bremer, an astronomer at the Institute of Millimeter Radio Astronomy (IRAM) and responsible for EHT observations on European telescopes.

With the IRAM telescope in Sierra Nevada (Spain), the powerful ALMA radio telescope in Chile and structures in Hawaii (United States) and Antarctica, the Event Horizon Telescope covers much of the planet.

With their multiple observations, astronomers seek to identify the immediate environment of a black hole.

According to theory, when matter is absorbed by the monster, it emits a light. The EHT project, capable of capturing the millimeter waves emitted by the environment of the black hole, had as objective to define the outline of the celestial body, the so-called event horizon.

Sagittarius A *, the first of the project's two targets, is located 26,000 light-years from Earth. Its mass is equivalent to four million times that of the sun.

Its congener of the M87 galaxy is "one of the most massive known black holes, 6 billion times more than our Sun and 1,500 times more than Sgr A *," says EHT. It is located 50 million light-years from Earth, "the proximity on the cosmic scale, but 2000 times more distant than Sgr A *," he adds.

lc-mh / alu / ra / erl / mr


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