Researchers Find Hidden Treasures in Archival MeerKAT Observations

A group of researchers from the Rhodes Centre for Radio Astronomy Techniques and Technologies (RATT) in South Africa, in partnership with collaborators from the South African Radio Astronomy Observatory (SARAO), Observatoire Paris Meudon, the University of Oxford, and the Breakthrough Listen initiative, have established a project to mine the MeerKAT telescope’s archive for previously overlooked transient radio sources. Their first two finds – including a stellar radio flare and exotic millisecond pulsars – are being published by Monthly Notices of the Royal Astronomical Society.

MeerKAT’s unique combination of sensitivity and sky coverage enable it to survey the sky with unprecedented speed. This makes the telescope an ideal instrument to search for sources that vary over time, including “transient” sources that appear and disappear suddenly. The telescope is also a powerful tool being used by the Breakthrough Listen initiative to search for technosignatures, or indicators of technology as a proxy for extraterrestrial intelligence. The Listen team has deployed dedicated hardware to MeerKAT to search for technosignatures alongside the telescope’s regular observations, but the new partnership is also taking advantage of the large amounts of data already acquired by MeerKAT and stored in its data archive.

“Previous mining of the MeerKAT data archive led to our discovery of an unusual object we called the RATT PARROT,” explains Distinguished Professor Oleg Smirnov, who leads the Rhodes University team. The PARROT is an unusual pulsar that was serendipitously discovered during processing of completely unrelated observations. “What prompted the discovery in the first place was its transient nature. This brought home the point that many more such transients must be lurking in MeerKAT data – and that it’s the telescope’s exquisite sensitivity that makes it possible to detect them. While dedicated transient search programs are already being pursued by other groups, we could see a way to start looking for these things semi-automatically, using essentially any MeerKAT imaging observation – and the archive already has over six years worth of observations that can be mined for such exotic transient sources.”

Despite only kicking off the project in March 2024, the team already has its first successes. The first was the detection of a number of millisecond pulsars (MSPs), particularly of the exotic “spider” variety. A spider pulsar revolves around a companion star in such a tight orbit that it “eats away” at it, stripping and accreting matter from the unfortunate companion. This can also cause the pulsar to regularly eclipse, thus manifesting itself as a transient source. All previously known MSPs have been detected via dedicated, highly specialised pulsar search observations. This is the first detection of MSPs in routine radio imaging data, which underscores the promise of this technique for finding more of these objects.

The team’s second find was a stellar radio flare. Such events are not unprecedented (after all, we often observe flares from our own Sun), but, owing to the large distances to other stars, remain fairly elusive. This particular star, at over 1300 parsecs away, is no neighbour, so the flare must have been a particularly powerful event to be detectable. The star is of a type called an RS CVn (named after the first such discovered star, RS in the constellation Canum Venaticorum). An RS CVn star also has a binary companion, and events such as flares are presumably due to matter ejected by the companion falling onto the star.

Curiously, the flaring RS CVn was detected in one of the follow-up observations that were done on the PARROT pulsar. “This reinforces the point that we should be seeing transients everywhere, if we just get smarter at looking for them”, explains Prof. Smirnov. “We found the PARROT through sheer blind luck, then requested a few follow-up observations to get to the bottom of things. Lo and behold, we’ve now caught a flaring star in one of those follow-ups. That’s not luck anymore – that’s the Universe telling us these things are all over the place! And we already have a few more surprises like this in the pipeline – watch this space.“

“The collaboration with our South African colleagues is a great example of the synergies between searches for interesting astrophysical objects, and the search for intelligent life beyond Earth,” explains Dr. Ian Heywood, Image Domain Technosignature Lead for the Breakthrough Listen program at the University of Oxford. “The Universe has a way of surprising us with the incredible variety of phenomena that arise as a result of the basic laws of physics. And if the same processes that gave rise to intelligent life, and technology, on Earth also operate elsewhere, instruments like MeerKAT provide our best chance to date of finding our cosmic neighbors.”

Contacts

Prof Oleg Smirnov, Rhodes Centre for Radio Astronomy Techniques & Technologies (RATT)
Email: o.smirnov@ru.ac.za

Website: ratt.center

www.physics.ox.ac.uk/research/group/breakthrough-listen

Institutional Information

The South African Radio Astronomy Observatory (SARAO) is a national facility of the National Research Foundation (NRF) and responsible for implementing South Africa’s strategic investment in radio astronomy, including leading South Africa’s involvement in the international Square Kilometre Array (SKA) project on behalf of the Department of Science, Technology and Innovation (DSTI). Its tasks include the development and operations of the state-of-the-art MeerKAT radio telescope in the Karoo and the geodesy and VLBI activities at the Hartebeesthoek Radio Astronomy Observatory (HartRAO). SARAO also implements the Africa Programme, which includes coordination of the African VLBI Network (AVN) for the eight SKA partner countries in Africa (Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia, and Zambia), as well as South Africa’s contribution to the infrastructure and engineering planning and construction for the SKA radio telescope.

Website: sarao.ac.za

Breakthrough Listen, headquartered at the University of Oxford, is the world’s most comprehensive search for “technosignatures”, or signs of intelligent life in the Universe. Listen collaborates with facilities around the globe, including many of the most powerful radio telescopes, as well as cutting-edge observatories operating in other regions of the electromagnetic spectrum. It is surveying one million nearby stars, the entire galactic plane and 100 nearby galaxies.

Website: breakthroughinitiatives.org