‘Blown away’: how SA man helped capture first black hole image
Pretoria astrophysicist is part of the international team working on the Event Horizon Telescope project that has just made history
Growing up in the Free State, Roger Deane, an astrophysicist from the University of Pretoria, had a good view of the Milky Way, inspiring his dreams to become an astronaut.
Now, the 36-year old has helped the world see the first images of a black hole, from a distant galaxy, Messier 87, in the constellation Virgo.
Black holes are formed when very massive stars collapse at the end of their life cycle.
Deane, speaking to media and his colleagues from Brussels, where the image was released, said what was “in the mind of astrophysicists is now in the eye of the world”.
“I’m still blown away by the image , it hasn’t really worn off yet,” he said on Wednesday.
Deane is part of the team working on the Event Horizon Telescope (EHT) project, an international collaboration which begun in 2012 in an attempt to directly observe the immediate environment of a black hole using a global network of Earth-based telescopes.
The EHT is a set of eight-ground based telescopes designed to simultaneously capture images of a black hole, 55 million light years away from Earth, from all corners of the globe.
A black hole has a mass 6.5 billion times that of the sun, absorbs all light and cannot be photographed. However, the photographs of the shadow are in line with what Albert Einstein’s theory of relativity predicted more than 100 years ago.
The telescopes together captured images of the black hole’s shadow, which results from the light emitted as objects fall and circulate into the hole.
The telescopes created data, which was analysed for more than six months by scientists across the globe, it was revealed at the media conference. Then a number of teams interpreted the data independently and turned it into an image to ensure there was no human error.
Project manager of EHT, Shepherd Doelman of the Center for Astrophysics, Harvard & Smithsonian, said: “We are giving humanity its first view of a black hole – a one-way door out of our universe”.
This is landmark in astronomy, an unprecedented feat accomplished by a team of more than 200 researchers, said an ETH press release.
Deane, who completed his master’s degree at Oxford University, is leading an astrophysics research group at UP.
He explained that to see such a large black hole so far away required an Earth-sized telescope, which no one “would be very happy with”.
But having telescopes at all corners of the world helped give the image the required sharpness.
The telescopes were at high altitude to prevent weather interference knocking out the radio waves.
The radio waves measured are 200 times smaller than the wavelength of light that the MeerKAT telescope observes in SA.
Deane said: “Just a small amount of water vapour in the atmosphere could completely erase the signature of the black hole shadow. This is why the EHT stations are at very high altitudes in some of the driest places on Earth.”
He and his master’s student Tariq Blecher built a theoretical model to help EHT scientists understand what they were seeing and to create a predicted image of a black hole.
Blecher, speaking from Pretoria, explained it was important that the predicted model matched the image the telescope captured.
Without a theoretical framework, what data scientists are seeing is “is all just numbers”.
The first step towards the SA involvement involved scientists looking at material going around the black hole and seeing how it moves before being sucked in, said Blecher.
Theorists would then measure how light is emitted from that material. The light is bent by the huge gravity of the hole, so it doesn’t move the way light does on Earth.
Then, Blecher and Deane used physics to predict how the telescopes would view this light without weather interference – in “perfect conditions”.
The duo’s picture of how the telescopes should detect the light was matched to the telescope image created from data, and proved to be very close.
Blecher’s master’s paper from Rhodes University on this telescope was cited in two of the six academic papers released on Wednesday describing the black holes.
Deane said it was a phenomenal vote of confidence that investment in astronomy by the department of science and technology was made such a priority. “We are reaping wonderful returns.”
He teaches a third-year physics course on observational astronomy at UP.
Much of his research is related to the MeerKAT radio telescope, which was built, and is operated by, the South African Radio Astronomy Observatory.
He explained why seeing a black hole matters.
“This year, 100 years ago, Einstein’s theory of general relativity was verified. You wouldn’t get much closer or more accurate (to where you wanted to be) on Google Maps if you didn’t have general relativity corrections.
“Google maps is a practical payoff of the general theory of relativity.
“Tests of the physical understanding of reality [like the telescope] may not give immediate payoffs, but when they do, pay-off is fairly big.”
Deane said next the EHT scientists want to look at a black hole in our galaxy, which is 1,000 times smaller.
He said he was born at the right time to be part of SA astronomy.
“I happened to do this at a pivotal stage in the growth of astronomy in this country. I am extremely grateful to all those who have made this possible. Had I been born 10 years earlier, my career would have been very different.”
Doelman concluded: “We have achieved something presumed to be impossible just a generation ago.”
“Breakthroughs in technology and the completion of new radio telescopes over the past decade enabled our team to assemble this new instrument designed to see the unseeable.”