Multimillion-rand SA telescope to investigate mysterious dark energy

A new multimillion-rand radio telescope will be launched on Friday to probe the deep mysteries of radio bursts and dark energy.

The instrument, dubbed HIRAX for the Hydrogen Intensity and Real Time Analysis eXperiment, will have its nucleus of 1 024 6m dishes in Carnarvon in the Northern Cape province, at the site of the MeerKAT radio telescope array.

One of the key research areas of the HIRAX is the investigation of mysterious dark energy, which is theorised to provide the energy for accelerated expansion of the universe.

"There is evidence for dark energy - super novae and other lines have demonstrated evidence for dark energy," Dr Kavilan Moodley, one of the principal HIRAX investigators, told News24.

'Tremendous breakthrough'

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Moodley obtained his PhD from Cambridge University and currently works at the University of KwaZulu-Natal. His main research interest lies in confronting cosmological theories with observational data.

"HIRAX will add the ability to measure how the universe expands at a critical time when dark energy was coming to dominate the expansion of the universe about seven to 12 billion years ago," he added.

Dark energy makes up about 70% of the universe and is theorised to have caused the expansion of the universe at an accelerated rate. Dark matter makes up 27% and so called "normal matter" - the stuff we can see - makes up less than 5%.

"If our model of dark matter is basically correct, then we should eventually be able to detect dark matter particles with experiments on Earth. If this is achieved, it would be a tremendous breakthrough," Professor Roy Maartens told News24.

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Maartens is a cosmologist who focuses on the dark energy problem and has published more than 200 papers. He is not directly involved in the HIRAX and from 2011, has held the Square Kilometre Array (SKA) Research Chair in Cosmology at UWC.

"Dark energy is more problematic, and unlikely to be detectable by Earth experiments. But probes of the Universe that are done by experiments like HIRAX could help us to rule out some of the models for dark energy. If the simplest model - the so-called vacuum energy or Lambda model - is ruled out, that would be a major breakthrough. But it would not be a final solution to the problem," he said.

The first two dishes are completed.
The first two dishes are completed. (Ben Saliwanchik)

MeerKAT, which is the precursor for the massive SKA, will be used in partnership with HIRAX to study neutral hydrogen, as astronomers work to map the expansion of the universe and understand the density of galaxies.

"We are actually measuring neutral hydrogen in the universe," said Moodley.

"The spread out nature of MeerKAT gives you better resolution and HIRAX is measuring hydrogen on very large scales," he added.

Puzzling phenomena

Moodley also indicated that the instrument would investigate the puzzling phenomena of fast radio bursts (FRBs).

READ: SA's MeerKAT astronomers score massive win in discovering super magnetic star secrets

These sudden releases of energy are thought to be related to powerful magnetic neutron stars called magnetars or the spinning remains of dead stars known as pulsars.

All eight dishes are completed.

All eight dishes are completed. (Ben Saliwanchik)

Very few repeating FRBs have been found, leading to speculation that they are random events.

But Moodley said that the HIRAX could deliver unprecedented research into FRBs.

"Since they found a repeating burst, some people are wondering whether they [FRBs] are from a magnetar.

"HIRAX can detect these events and monitoring whether they repeat or not."

While the instrument will have its centre in the Karoo, the team will also place telescopes - known as outrigger arrays - in partner African countries.

The HIRAX team poses for a photograph.
The HIRAX team poses for a photograph. (Cynthia Chiang)

Radio astronomy allows academics to use interferometry to precisely map the location of FRBs.

"When we get a signal in the main array in the Karoo, we'll send the signal to those other outrigger arrays.

"With these outrigger arrays, we can localise FRBs," said Moodley.

'Ground breaking research'

He could not contain his excitement at the prospect of the impact of the research: "This is groundbreaking research."

Swiss researcher André Maeder argued that his research suggested that dark matter and dark energy may not exist.

But while Moodley regarded that theory as "interesting", he said that new equipment was giving astronomers more tools to understand the natural world.

"It's an interesting theory, but theories have to be borne out by the data," he said.

Maartens concurred, saying: "Maeder claims to have a new theory of gravity which also does not need dark energy - but until this theory is developed to the point that it can explain all the observations, any claim against dark matter and dark energy is premature."

The HIRAX project costs R70m and is funded by the University of KwaZulu-Natal and the Department of Science and Technology through the National Research Foundation.

"The project will help South Africa develop innovative solutions, particularly in instrumentation and big data processing, directly impacting other economic sectors through technology transfer," said Minister Mmamoloko Kubayi-Ngubane.

Moodley said that the cost of the instrument was relatively cheap when compared to similar international projects.

"We are competing with $15bn experiments; we have the site with low radio interference. Our dishes are relatively cheap and we can build a lot of them."

For Maartens, the difficulty of the question around dark energy is not something to fear.

"Let me make a final point: Astrophysicists are not scared of questions that cannot be answered easily. Progress in physics allows us to understand more - but it also means that we can ask even harder questions which cannot be easily answered. It takes time to crack big problems - there is no need to panic."

HIRAX by the numbers:

Dishes

1024

Size

6m

Operating frequency

400MHz - 800MHz

Field of view

5° - 10°

Cost

R70m


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