Over 1,000 dishes to shine new light on ‘dark energy’


Over 1,000 dishes to shine new light on ‘dark energy’

New project in the Karoo will use hydrogen gas to unravel one of the most perplexing puzzles in physics


Looking very much like the massed battle shields of a phalanx of ancient Greek warriors, more than 1,000 radio astronomy dishes will be lined up in the Karoo desert shortly.
Arranged in a rectangle pointing to the heavens, their purpose is to shed more light on “dark energy”, perplexing flashes of light and other unsolved mysteries of the universe.
The R70m project, known as Hirax, will see the installation of 1,024 radio receiver dishes (each 6m wide) in one of the few remaining regions of the world that is unpolluted by wifi, cellphone, television and other electrical interference.Hirax (Hydrogen Intensity and Real Time Analysis eXperiment) will create a powerful radio telescope that will help scientists peer back in time to study background radiation left over from the Big Bang (an explosive event 13.7 billion years ago that astrophysicists associate with the creation of the universe).
But unlike optical telescopes, which gather information from light sources in the heavens, the Hirax compact radio telescope gathers data from neutral hydrogen gas and converts this into visual images.
Though much of the infrastructure will be located in the “radio-quiet” remoteness of the Karoo, the experiment will be managed from Durban by the University of KwaZulu-Natal (UKZN), in collaboration with several other local and foreign universities and research bodies.
Explaining the project at the official launch last week on August 17, SA Radio Astronomy Observatory MD Dr Rob Adam said it was critical to use a combination of techniques to gather clearer images of the universe.
Large optical telescopes such as SALT (Southern African Large Telescope) were very useful in magnifying the resolution of remote “blobs” of light in the heavens.But when using radio telescopes it was possible to gather a very different perspective of these blobs.
“With radio telescopes you see something quite different. You get different information,” he said.
Adam notes that the view of the Milky Way is clouded by “dust” when viewed through an optical telescope, whereas radio telescopes allow the viewer to discern all sorts of peculiar features that were not visible previously.
While ordinary mortals cannot “see” radio waves, different colours can be assigned different frequencies to make them visible. For example, low-frequency waves are depicted as red, high-frequencies as blue and middle-frequencies as green.Another advantage is that radio telescopes can gather information during the day and night, unlike optical telescopes which rely mainly on the brighter light of the night skies.
Professor Kavilan Moodley, the UKZN principal investigator of the Hirax project, says the main focus will be the study of “dark energy”.
“What is dark energy? We don’t really know,” Moodley admits. “It remains one of the most perplexing puzzles in physics.”
In simplistic terms, astronomers and physicists suggest that dark energy is a repulsive gravity force that is pushing the universe apart.
Moodley hopes that the first 128 dishes will be installed near the town of Carnarvon within the next year, with the full complement of 1,024 dishes in place by 2021.
Bursts of curiosity
The second major focus of Hirax will be the study of “fast radio bursts” (FSBs), says Professor Jonathan Sievers, co-principal investigator.
Sievers, a cosmologist affiliated to UKZN and McGill University in Canada, describes FSBs as very fast flashes of light that last about one thousandth of a second.
“We have no idea about what these things are. We know that they come from outside the Milky Way, but they remain cosmic enigmas.”So far, says Sievers, only about 40 of these distant split-second bursts had been located.
The major difficulty with locating these momentary flashes was that observers had to be looking for them in the right place and at the right time.
“The drunk man can look for his keys under the street lamp, but how do you see an FSB if you don’t know where to look for them?”
“We think Hirax will be a game-changer and that it could position dozens of FSBs every day.”
He also hopes that the new Karoo telescope could potentially double the number of known pulsars (very dense star remnants that appear to blink or pulse brightly, like distant celestial lighthouses).
Bandwidth gobbler
Back on Earth, however, processing and decoding so much data is expected to chew up vast volumes of bandwidth.According to Moodley, HIRAX will collect data at a rate of about 6.5 terabits per second – a volume rate that would be comparable to all of Africa’s current international bandwidth.Millions of Earthlings, beset by poverty, conflict and all manner of other dilemmas, may ponder the relevance of such expensive and ambitious research initiatives.
In response, Science and Technology Minister Mmamoloko Kubayi-Ngubane had this to say:
“To those who always wonder why projects like this are important, I will say to them in the words of the American cosmologist, Neil [deGrasse] Tyson that: ‘Space exploration is a force of nature unto itself that no other force in society can rival. Not only does that get people interested in sciences and all the related fields, [but] it transforms the culture into one that values science and technology, and that’s the culture that innovates. And in the 21st century, innovations in science and technology are the foundations of tomorrow’s economy’.”The Hirax project will be about 20km from the 64-dish MeerKAT array, the precursor to SA’s Square Kilometre Array (Ska). The project will also involve several universities and research bodies, including UKZN, University of Cape Town, University of the Western Cape, Stellenbosch University, Rhodes, Durban University of Technology, Botswana International University of Science and Technology, McGill University, University of Toronto, Yale, California Institute of Technology, University of Wisconsin, University of Geneva, and University of Oxford.

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