Cape Town - An unexplained astronomical object has been observed by a team of South African, US and Australian scientists, with the help of machine learning.
Led by Michelle Lochner, who holds a joint position at the University of the Western Cape and the South African Radio Astronomy Observatory, the team combed through data generated in the MeerKAT Galaxy Cluster Legacy Survey (MGCLS), a programme of observations of 115 galaxy clusters, run on South Africa’s MeerKAT Radio Telescope between June 2018 and June 2019.
Ultimately, they found the “seventh sighting” of a newly discovered class of radio sources, known as odd radio circles. ORCs were so named because of their distinctive giant rings made up of radio waves and, in keeping with the Lord of the Rings theme, the Lochner team have chosen to name their finding Sauron, short for a Steep And Uneven Ring Of Non-thermal radiation.
In Sauron’s discovery, the team had deployed an “anomaly detection framework” with built-in machine learning capabilities that Lochner developed with collaborators at the University of Cape Town. “Astronomaly” is designed to pick up on any anomalies in large amounts of observation data, but curated to the user’s specific preferences.
Interesting anomalies
“It uses active learning to combine the raw processing power of machine learning with the intuition and experience of a human user, enabling personalised recommendations of interesting anomalies,” she said.
Instead of having to comb through 6 000 individual images generated by the MGCLS, the researchers had to only focus on the first 60 that Astronomaly flagged as anomalous.
However, for all the excitement over the discovery, Lochner and her team have yet to confirm that Sauron is indeed an ORC. Since first detected in observations by the Australian Square Kilometre Array Pathfinder in 2019, only six confirmed sightings have been recorded. Scientists are figuring out what exactly ORCs are, and “are yet to come up with a definitive taxonomic classification”.
“Sauron could plausibly be the result of the enormous release of energy resulting from the rare merger of two of these ‘supermassive’ black holes,” suggests one of the team members, Lawrence Rudnick, Professor Emeritus at the University of Minnesota.
To come up with more concrete answers, Lochner and her collaborators are pitching for more observation time on MeerKAT.
The team hopes to put the object front and centre of an observation, while scanning different frequency bands. In this way, they hope to glean more insights on, among other things, Sauron’s magnetic fields and the various energies of electrons around it, while also, hopefully, detecting the presence of jets. The jets, for instance, would serve as evidence of a collision between supermassive black holes.
“If our proposed observations can pin this down, we can examine the physics of what happens in such extreme, elusive mergers, and the implications for future detections of gravitational waves, galaxy evolution and the production of relativistic particles,” Rudnick added.
“Sauron, we believe, is almost like a holotype of such active galactic nuclei, against which others can be compared and measured. Its unique physics could certainly shed light on what is happening in other ORCs,” Lochner said.
*This article was originally published in Nature.
Cape Times