New telescope array will capture the first-ever photograph of a black hole

• Global network of 50 telescopes will capture 'shadow' of black hole
• Black holes normally invisible as gravity sucks in light
• Crucial test for Einstein's theory

An illustration of a black hole: A new telescope array could allow scientists to photograph a black hole for the first time - teaming up 50 radio telescopes around the world into a global telescope that will capture the 'shadow' of a black hole for the first time

A new telescope array could allow scientists to photograph a black hole for the first time - teaming up 50 radio telescopes around the world into a global telescope that will capture the 'shadow' of a black hole for the first time.
Scientists will meet on Wednesday 18th to discuss the project, which will also test Einstein's Theory of General Relativity.
The project - called the Event Horizon Telescope - could capture the first images of the huge black hole at the centre of our own galaxy, the Milky Way.
The 'supermassive black hole' is four million times the mass of our sun, but so far away that it appears to astronomers about the same size as a grapefruit on the moon.
The Event Horizon in the telescope's name refers to the boundary at the edge of a black hole beyond which the laws of physics  cannot describe what happens.
It is a 'point of no return' - from which no light or radiation can escape.
Because of it, black holes are invisible from Earth.
The idea of black holes was first raised by Einstein in his General Theory of Relativity, and has been confirmed by decades of measurements and observations of space.

 

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But it has been impossible to directly 'see' a black hole - the gravity that surrounds the objects is so intense that even light cannot escape.
Black holes warp space and time around them.

'Nobody has ever taken a picture of a black hole. We are going to do just that. Once we see its shadow, there will be no doubt,' says Professor Psaltis

'Nobody has ever taken a picture of a black hole,' says Dimitrios Psaltis, an associate professor of astrophysics at the University of Arizona's Steward Observatory. 'We are going to do just that.'
'Even five years ago, such a proposal would not have seemed credible,' said Sheperd Doeleman, assistant professor at MIT and principal investigator on the project. 'Now we have the technological means to take a stab at it.'
Black holes are the most extreme environment you can find in the universe,' Doeleman said.
Black holes live up to their name - they 'pull in' light and all other energy as efficiently as they suck in matter, so no radiation reaches Earth.
They appear as a blank space to telescopes. But a 'glow' round the outside could let scientists see the outline.
'As dust and gas swirls around the black hole before it is drawn inside, a kind of cosmic traffic jam ensues,' says Doeleman.
'Swirling around the black hole like water circling the drain in a bathtub, the matter compresses and the resulting friction turns it into plasma heated to a billion degrees or more, causing it to 'glow' – and radiate energy that we can detect here on Earth.'
By imaging the glow of matter swirling around the black hole before it goes over the edge of the point of no return, scientists can see the outline of the black hole, also called its shadow.

The team is connecting up to 50 radio telescopes scattered around the globe, including the Submillimeter Telescope on Mt. Graham in Arizona, telescopes on Mauna Kea in Hawaii (pictured) and the Combined Array for Research in Millimeter-wave Astronomy in California

'So far, we have indirect evidence that there is a black hole at the center of the Milky Way,' Psaltis said. 'But once we see its shadow, there will be no doubt.'

Even though the black hole suspected to sit at the center of our galaxy is a supermassive one at four million times the mass of the Sun, it is tiny to the eyes of astronomers.
Smaller than Mercury's orbit around the Sun, yet almost 26,000 light years away, it appears about the same size as a grapefruit on the moon.

'To see something that small and that far away, you need a very big telescope, and the biggest telescope you can make on Earth is to turn the whole planet into a telescope,' says Marrone.

The team is connecting up to 50 radio telescopes scattered around the globe, including the Submillimeter Telescope on Mt. Graham in Arizona, telescopes on Mauna Kea in Hawaii and the Combined Array for Research in Millimeter-wave Astronomy in California.
The global array will include several radio telescopes in Europe, a 10-meter dish at the South Pole and potentially a 15-meter antenna atop a 15,000-foot peak in Mexico.

'In essence, we are making a virtual telescope with a mirror that is as big as the Earth,' Doeleman said. 'Each radio telescope we use can be thought of as a small silvered portion of a large mirror. With enough such silvered spots, one can start to make an image.'

'Every year, we increase its capabilities by adding more telescopes, gradually sharpening the image we see of the black hole.'

'We will be able to actually see what happens very close to the horizon of a black hole, which is the strongest gravitational field you can find in the universe,' Psaltis said. 'No one has ever tested Einstein's Theory of General Relativity at such strong fields.'

General Relativity predicts that the bright outline defining the black hole's shadow must be a perfect circle. According to Psaltis, whose research group specializes in Einstein's Theory of General Relativity, this provides an important test.

'If we find the black hole's shadow not to be circular, it means Einstein's Theory of General Relativity must be flawed,' he said.
Black holes remain among the least understood phenomena in the universe.
Ranging in mass from a few times the mass of the Sun to billions, they appear to coalesce like drops of oil in water.
Most if not all galaxies are now believed to harbor a supermassive black hole at their center, and smaller ones are scattered throughout.
Our Milky Way is known to be home to about 25 smallish black holes ranging from 5 to 10 times the Sun's mass.

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