Black hole: scientists reveal first true image

Astronomers have unveiled the first photo of a black hole, situated in a galaxy 50 million light years away.

The first true image of a black hole. Picture: AFP PHOTO / EUROPEAN SOUTHERN OBSERVATORY

Astronomers have unveiled the first photo of a black hole, one of the star-devouring monsters scattered throughout the Universe and obscured by impenetrable shields of gravity.

The image of a dark core encircled by a flame-orange halo of white-hot gas and plasma looks like any number of artists’ renderings over the last 30 years.

But this time, it’s the real deal.

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 light years 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.

Most speculation had centred on the other candidate targeted by the Event Horizon Telescope Sagittarius A*, the black holeat the centre of our own galaxy, the Milky Way.

By comparison, Sag A* is only 26,000 light years from Earth.

Locking down an image of M87’s supermassive black hole at such distance is comparable to photographing a pebble on the Moon.

European Space Agency astrophysicist Paul McNamara called it an “outstanding technical achievement”.

It was also a team effort.

“Instead of constructing a giant telescope that would collapse under its own weight, we combined many observatories,” Michael Bremer, an astronomer at the Institute for Millimetric Radio Astronomy (IRAM) in Grenoble, 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 are at least a million times bigger than the Sun. Both Sag A* and M87 fall into this category.

The EHT is unlike any stargazing instrument ever devised.

“Instead of constructing a giant telescope we combined several observatories as if they were fragments of a giant mirror,” Michael Bremer, an astronomer at the Institute for Millimetric Radio Astronomy in Grenoble, told AFP.

Eight such radio telescopes scattered across the globe — in Hawaii, Arizona, Spain, Mexico, Chile, and the South Pole — zeroed in Sag A* and M87 on four different days in April 2017.

Each is at least a big as a football pitch. Together, they form a virtual telescope more than 12,000 kilometres across, the diameter of Earth.

Data collected by the far-flung array was to be collated by supercomputers at MIT in Boston and in Bonn, Germany.

Albert Einstein’s theory of general relativity could be tested. Picture: Fred Stein Archive

“The imaging algorithms we developed fill the gaps of data we are missing in order to reconstruct a picture,” the team said on their website.

Astrophysicists not involved in the project, including McNamara, are eagerly — perhaps anxiously — waiting to see if the findings challenge Einstein’s theory of general relativity, which has never been tested on this scale.

The LIGO experiments from 2015 detected signature ripples in the curvatures of time-space during the black hole merger.

“Einstein’s theory of general relativity says that this is exactly what should happen,” McNamara said.

But those were tiny black holes compared with either of the ones under the gaze of the EHT.

“Maybe the ones that are millions of times more massive are different — we just don’t know yet,” McNamara said.

AFP