A University of Pretoria astrophysicist, Professor Roger Deane, was part of an international group of scientists who made history by capturing the first ever image of a black hole.
The results were presented simultaneously by researchers in Brussels, Santiago de Chile, Taipei, Tokyo and Washington.
“This major discovery provides visual evidence for the existence of black holes and pushes the boundaries of modern science,” the European Commission in Brussels said in a statement.
Deane and his team from the university had the task of developing simulations from the “Earth-sized” telescope used to make the historic discovery. These simulations mimic the data coming from the real instrument, which is made up of a number of antennae across the globe, mimicking the imagery to help scientists get a better picture of what they are looking at.
The years’-long effort to photograph the Messier 87 black hole was the result of analysing data produced by radio telescopes scattered around Earth, collectively known as Event Horizon. The discovery gives scientists the opportunity to probe general relativity in an extreme environment, the interplay between supermassive black holes and galaxies, and more.
If popular science always told us that black holes could not be seen, on Wednesday humanity’s view of these cosmic curiosities shifted forever.
The collaboration of scientists reveals what is called the “event horizon”, the boundary at the edge of a black hole where the gravitational pull is so strong that no conventional physical laws apply and nothing can escape. The image released on Wednesday shows the shadow of the hole at the centre of glowing plasma.
In the picture we are “looking at a region we’ve never looked at before, a region we cannot imagine being there”, said Heino Falcke, Professor of Astroparticle Physics and Radio Astronomy at the Radboud University Nijmegen and chair of the EHT Science Council.
“It feels like looking at the gates of hell, the end of space and time, the point of no return.”
The discovery opens up more questions for scientists to explore, including “some deep fundamental physics questions that still need to be solved,” said Falcke.
The two big theories that describe the universe – quantum physics and general relativity – break down at the edge of black holes, he said, and now “it becomes a real problem”.
The existence of black holes, one of the more mysterious objects in the cosmos, had been universally accepted even though little is known about them. Black holes form from remnants of a large star that dies in a supernova explosion. Scientists estimate there could be as many as a 100 million black holes in the Milky Way, according to Nasa.
The EHT’s pictures show the black hole at the centre of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster. This black hole resides 55 million light-years from Earth and has a mass 6.5-billion times that of the sun, the commission said in its statement.
Scientists say they observed the source for four days, during which the size remained the same, allowing them to measure the contrast between the ring itself and the central darkness.
The image also suggests that something – either the matter around it or the black hole itself – was rotating clockwise, astrophysicist Monika Moscibrodzka from Radboud University Nijmegen said.
Deane was in Brussels for the announcement.
In a Skype interview, he told journalists that simulating the entire instrument produced an image of what the black hole should look like. He added that the simulations would take other aspects into consideration, such as the thermal dynamics around the black hole, the physics of every antenna used to capture the actual image and even empirical data on how the telescopes wobble. They would then note how that changed the perfect view of the black hole shadow as if the image was taken from a close-up position.
“As with any major physics experiment, one needs to understand the effects that the instrument itself may have on the data. In the case of the EHT, we built a simulation package that physically modelled a number of non-desirable effects that prevent one from seeing any sort of black hole shadow feature,” Deane said.
“This accurate simulation of the telescope enables astronomers to better understand the real observations, discriminate between theoretical black hole shadow models and insights into the characteristics and performance of the telescope itself.”
Deane explained that the image was only the beginning of their investigation, but that he was still blown away by the actualisation of the image, which is a start to confirming Albert Einstein’s theory of relativity.
“I’m just proud and honoured to play my small part in this amazing international team.”
Deane’s group will now focus on expanding their simulations to model a case in which light from the black hole may have preferred orientation, performing detailed simulations on new prospective sites, and exploring a range of probabilistic modelling techniques to extract the properties of the black hole shadow.
The vice-chancellor and principal of the university, Professor Tawana Kupe, congratulated Deane on his contribution.
“This young scientist is an inspiration to scientists on the African continent. Our staff and students are innovative and creative thinkers who excel in cutting-edge research and this discovery is a great example of what can be achieved if we work together across borders and disciplines.”
Eight telescopes across the globe participated in the observations in 2017. They have been connected to create a virtual Earth-sized telescope allowing it to “measure the size of the emission regions of the two super-massive black holes with the largest apparent event horizons”, the EHT says on its website. The telescopes are scattered across the world, from volcanoes in Hawaii to the Atacama desert in Chile to Antarctica and Europe.
The researchers said they hoped the image of M87 would help them analyse another black hole, known as the Sagittarius A*, which sits at the centre of the Milky Way with a mass of around 4.3 million times that of the sun and located 25,000 light years from Earth.
The scientists said they focused their efforts on M87 first since the black hole moves a thousand times slower than the Sagittarius A*, making it easier to capture. DM
Magenta has no physical wavelength. It thus does not "exist" strictly speaking. Rather our brains are telling us that we are seeing "not green".
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