Celebrating MeerKAT’s boundless scope for discovery

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As South Africa’s greatest astronomical project comes of age, researchers mark its achievements

The discovery of 49 new galaxies in a few hours, announced earlier this year, was the latest testament to the value of South Africa’s MeerKAT telescope. Six years after its inauguration, it is finally proving to be much more than an iteration of the future giant radiotelescope Square Kilometre Array.

The 64-dish MeerKAT radio telescope array was built between 2014 and 2018 through South African government funding some 90km from the nearest town.

The recent trove of new galaxies — with dozens more waiting to be revealed in unpublished data — is a demonstration to the sensitivity it has reached. Institutions and researchers from around the world, including South Africa, Kenya, the UK, the Netherlands, Italy, the USA, France, Australia and Germany are lining up to use the instrument. A major technical update that started this year will further hone its sensitivity. And a whole generation of PhD students and postdocs trained in its operation have revitalized African astronomy.

MeerKAT consists of 64 antennas, each 13.5 metres in diameter, stretching over an area of eight kilometres. The project, 90 kilometres from Carnarvon in the Northern Cape, took a decade from conception to conclusion and was funded by the South African government.

There are eight large Survey Projects (LSP) under MeerKAT and 300 smaller projects. Since the publication of the MeerKAT team’s first paper in 2019 in Nature, describing giant radio bubbles surrounding the Galactic Centre of the Milky Way, the affiliated researchers have produced more than 300 papers. Among the most recent is a study in the Monthly Notices of the Royal Astronomical Society, by an international team that describes 49 new galaxies.

Nicknamed the 49ers in a nod to the 1849 California gold rush, the newly identified galaxies were detected courtesy of faint radio waves emitted by the gas known as neutral hydrogen (or HI). They were discovered serendipitously when the team was analysing data collected over just three hours in April 2021.

“We were aiming to study just one system in that patch of sky; we weren’t expecting these galaxies to be there,” says Ed Elson, an astrophysicist with the University of the Western Cape in South Africa.

Most star-forming galaxies are known to be found within rotating, pancake-shaped discs of gas and dust that fuel the formation of stars.

“That star-formation process is the dominant evolutionary mechanism when it comes to galaxies,” says Elson.

Preliminary results already point to the discovery of yet another 80 galaxies, says project leader Marcin Glowacki, a research fellow at Curtin University’s node of the International Centre of Radio Astronomy Research (ICRAR), Australia.

A previous study conducted with Australia’s Parkes Telescope between 1997 and 2002 that looked at the exact same slice of the sky was not able to detect the galaxies spotted in just three hours with MeerKAT.MeerKAT’s improved sensitivity and larger frequency bandwidth allowed it to look for star-forming gas at greater distances, improving the odds of making new discoveries.

“It was able to make all these detections that had not been seen before,” observes Glowacki.

In fact, in recognition of their “spectacular advances in radio astronomy,” the Royal Astronomical Society presented the MeerKAT team at large with its Group Achievement Award in 2023.

Because of its precision and sensitivity, the MeerKAT is much sought after in Africa and beyond.

Fernando Camilo, chief scientist of the South African Radio Astronomy Observatory (SARAO), the national facility that built and operates MeerKAT, at the recent MeerKAT@5 conference in Stellenbosch, South Africa. Credit: Engela Duvenage

“MeerKAT is already a very popular telescope. Unfortunately, we can currently only accommodate roughly a quarter of the projects and ideas that scientists around the world submit,” says Fernando Camilo, chief scientist of the South African Radio Astronomy Observatory (SARAO), the national facility that built and operates MeerKAT.

He is excited about the installation of the first 14 dishes of the MeerKAT+ expansion, funded by SARAO, the Max Planck Society in Germany, and Italy’s Istituto Nazionale di Astrofisica. In February 2024, the first dish was delivered, with the remaining 13 expected to follow in the coming year.

Significant improvement

SARAO managing director, Pontsho Maruping, says MeerKAT+ will significantly improve the sensitivity, angular resolution and quality of detailed radio images of faint radio sources.

The 14 MeerKAT+ dishes will be as sensitive as about 21 MeerKAT dishes, adds Camilo, resulting in an array 1/3 more sensitive than the existing 64-dish one.

“Surveys of a portion of the sky could take much less telescope time than currently needed to get the same level of sensitivity. That can be very significant if you want to use hundreds or thousands of hours of telescope time to achieve some goal,” explains Camilo.

In the next decade, MeerKAT, will integrate into the mid-frequency component of the Square Kilometre Array’s (SKA) first phase, to be built in Africa and Australia. SKA will be the biggest radio observatory in the world. It is expected to operate over a wide range of frequencies through two telescopes, operating on hundreds of dishes and thousands of antennas.

The SKA-Low telescope is located in Australia, and the mid telescope in South Africa, where MeerKAT is. Construction began in December 2022, and the first phase of the project is expected to be operational by 2029. The SKA-designed dishes have more efficiently engineered surfaces and a larger main reflecting surface of 15 meters across (compared to 13.5 meters for MeerKAT). Each will stand up to 150 kilometers apart (compared to 8 kilometers for MeerKAT). The project is expected to collect some 700 petabytes of data annually, which represents the storage space of 1 million laptops.

Preparing the next generation of astronomers

SARAO has also awarded more than 1,000 scholarships to science and engineering students and trained a team of future astronomers that will help develop the field and cater for the expansion of the project’s scope. Glowacki, for one, had initially joined the LSP called “Looking at the Distant Universe with the MeerKAT Array (LADUMA)” in 2018 as a postdoctoral researcher at the University of the Western Cape (UWC) in South Africa. LADUMA will collect 3,000 hours of imagery of one part of the sky to shed light on galaxy evolution happening as far as 8 billion years back in cosmic time.

Glowacki soon detected a megamaser, a phenomenon he describes as “akin to giant lasers on a galaxy-sized scale, powered by a huge amount of star formation happening after two galaxies merge to form a larger one.” Nicknamed Nkalakatha (or big boss, in isiZulu), it was at the time the most distant megamaser yet recorded, according to a 2022 paper in Astrophysical Journal Letters involving 70 LADUMA scientists.

“MeerKAT lends itself quite well to student projects and training new people to develop essential skills for working with large data and radio telescopes,” Glowacki says. In fact, it was a UWC computer science student, called Zolile Tibane, who named the Nkalakatha meamaser.

Camilo explains that the science from MeerKAT-related projects is the result of collaborative research efforts spanning borders and institutions. He says such international collaborations open new windows on the universe, on subjects like the Milky Way, spinning pulsars, supermassive black holes, dark matter and the first stars. It stimulates technological innovation and career opportunities in engineering, astronomy and physics.

A SARAO bursary programme in South Africa has already seen 151 PhDs graduate, including students from African partners in Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia, and Zambia.

Among these graduates is Charles Takalana, former head of secretariat at the African Astronomical Society (AfAS) who was recently appointed as deputy director of the International Astronomical Union’s (IAU) Office of Astronomy for Development.

“MeerKAT has reignited efforts into African astronomy. In August 2024, Africa will for the first time host the general assembly of the IAU, in Cape Town,” he said at the recent MeerKAT@ 5 conference in Stellenbosch, South Africa.

doi: https://doi.org/10.1038/d44148-024-00206-7

Source: https://www.nature.com/articles/d44148-024-00206-7

References

Heywood, I., Camilo, F., Cotton, W.D. et al. Inflation of 430-parsec bipolar radio bubbles in the Galactic Centre by an energetic event. Nature 573, 235–237 (2019). https://doi.org/10.1038/s41586-019-1532-5
M Glowacki, L Albrow, T Reynolds, E Elson, E K Mahony, J R Allison, A serendipitous discovery of H I-rich galaxy groups with MeerKAT, Monthly Notices of the Royal Astronomical Society, Volume 529, Issue 4, April 2024, Pages 3469–3483, https://doi.org/10.1093/mnras/stae684
Glowacki, Marcin, et al. “Looking at the Distant Universe with the MeerKAT Array: Discovery of a Luminous OH Megamaser at z> 0.5.” The Astrophysical journal letters 931.1 (2022): L7.