LAST UPDATE | 10 Apr 2019
THE FIRST EVER image of a black hole, showing the event horizon, has been released.
Scientists unveiled the first results from the Event Horizon Telescope (EHT), conceived precisely for that purpose, this afternoon.
It has been a long wait, and is a discovery first predicted by Albert Einstein which now further bolsters his theory of relativity.
Scientists have been puzzling over invisible “dark stars” since the 18th century, but never has one been spied by a telescope, much less photographed.
The supermassive black hole now immortalised by a far-flung network of radio telescopes is 50 million lightyears away in a galaxy known as M87.
“It’s a distance that we could have barely imagined,” Frederic Gueth, an astronomer at France’s National Centre for Scientific Research (CNRS) and co-author of studies detailing the findings, told AFP.
The image shows matter being superheated as it is torn apart by the black hole’s strong gravitation field.
As not even light can escape a blackhole, the centre cannot be seen.
“Over the years, we accumulated indirect observational evidence,” said Paul McNamara, an astrophysicist at the European Space Agency and project scientist for the LISA mission that will track massive black hole mergers from space.
In September 2015, for example, the LIGO gravitational wave detectors in the United States measured two black holes smashing together.
“X-rays, radio-waves, light -– they all point to very compact objects, and the gravitational waves confirmed that they really are black holes, even if we have never actually seen one,” McNamara told AFP.
Ripples in time-space
A black hole is a celestial object that compresses a huge mass into an extremely small space. The more mass, the larger the black hole.
At the same scale of compression, Earth’s mass would fit inside a thimble, while the Sun’s would be a mere six kilometres from edge to edge.
There are two types.
Garden-variety black holes — up to 20 times more massive than the Sun — form when the centre of a very big star collapses in on itself.
So-called supermassive black holes, like the one at the centre of M87, are at least a million times bigger than the Sun.
The EHT is unlike any star-gazing instrument ever devised.
Eight such radio telescopes scattered across the globe — in Hawaii, Arizona, Spain, Mexico, Chile, and the South Pole — zeroed in M87 on four different days in April 2017.
Knit together “like fragments of a giant mirror,” in Bremer’s words, they formed a virtual observatory some 12,000 kilometres across — roughly the diameter of Earth.
In the end, M87 was more photogenic. Sag A* – the black hole at the centre of our galaxy and another candidate for the first image – was too “active” to capture a clear picture, the researchers said.
“The telescope is not looking at the black hole per se, but the material it has captured,” a luminous disk of white-hot gas and plasma known as an accretion disk, said McNamara, who was not part of the team.
“The light from behind the black hole gets bent like a lens.”
The unprecedented image — so often imagined in science and science fiction — has been analysed in six studies co-authored by 200 experts from 60-odd institutions and published Wednesday in Astrophysical Journal Letters.
CNRS astrophysicist Jean-Pierre Luminet, author in 1979 of the first digital simulation of a black hole, said:
I never thought that I would see a real one in my lifetime.
© – AFP 2019, additional reporting by Nicky Ryan
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