Capturing a Massive Black Hole

A halo of gas surrounding a black hole.
(Note: this is not an artist's rendering.)

"No single telescope is powerful enough to image the black hole. So, in the biggest experiment of its kind, Prof Sheperd Doeleman of the Harvard-Smithsonian Centre for Astrophysics led a project to set up a network of eight linked telescopes. Together, they form the Event Horizon Telescope and can be thought of as a planet-sized array of dishes.
Each is located high up at a variety of exotic sites, including on volcanoes in Hawaii and Mexico, mountains in Arizona and the Spanish Sierra Nevada, in the Atacama Desert of Chile, and in Antarctica.

A team of 200 scientists pointed the networked telescopes towards M87 and scanned its heart over a period of 10 days. The information they gathered was too much to be sent across the internet. Instead, the data was stored on hundreds of hard drives that were flown to a central processing centres in Boston, US, and Bonn, Germany, to assemble the information. Prof Doeleman described the achievement as 'an extraordinary scientific feat.'
'We have achieved something presumed to be impossible just a generation ago,' he said.


Prof Heino Falcke, of Radboud University in the Netherlands, who proposed the experiment, told BBC News that the black hole was found in a galaxy called M87. 'What we see is larger than the size of our entire Solar System,' he said. 'It has a mass 6.5 billion times that of the Sun. And it is one of the heaviest black holes that we think exists. It is an absolute monster, the heavyweight champion of black holes in the Universe.'"

- From the April 10th BBC report: First ever black hole image released.


"The physicist Stephen Hawking's greatest early-career contribution to physics was the idea of 'Hawking radiation' - that black holes aren't actually black, but emit small amounts of radiation over time. The result was hugely important, because it showed that once a black hole stops growing, it will start to very slowly shrink from the energy loss.

But the Event Horizons Telescope didn't confirm or deny this theory, Bonning said, not that anyone expected it to. Giant black holes like the one in Virgo A, she said, emit only minimal amounts of Hawking radiation compared to their overall size. While our most advanced instruments can now detect the bright lights of their event horizons, there's little chance that they will ever tease out the ultra-dim glow of a supermassive black hole's surface.

So what did we actually learn from this image?

First, physicists learned that Einstein was right, once again. The edge of the shadow, as far as the Event Horizons Telescope can see, is a perfect circle, just as physicists in the 20th century working with Einstein's equations of general relativity predicted. 'I don't think anyone should be surprised when yet another test of general relativity passes,' Bonning said. 'If they had walked on stage and said that general relativity had broken, I would have fallen off my chair.'

The result with more immediate, practical implications, she said, was that the image enabled scientists to precisely measure the mass of this supermassive black hole, which sits 55 million light-years away at the heart of the Virgo A galaxy."

- From the April 10th LiveScience article: 3 Huge Questions the Black Hole Image Didn't Answer.