ORCs are giant, faint rings of radio emission surrounding galaxies, visible only in radio wavelengths and composed of relativistic, magnetised plasma. First identified in 2019, only a few confirmed examples exist, most spanning 10-20 times the diameter of the Milky Way.

The newly identified source, designated RAD J131346.9+500320, lies at redshift ~0.94, when the universe was roughly half its current age. It is the most distant and energetic ORC known, and notably features two intersecting rings - only the second such case ever observed.

Researchers from the University of Mumbai made the discovery through the RAD@home Astronomy Collaboratory, a citizen science platform, using data from the Low-Frequency Array (LOFAR), the world's largest and most sensitive low-frequency radio telescope.

"This work shows how professional astronomers and citizen scientists together can push the boundaries of scientific discovery," said Dr Ananda Hota, founder of RAD@home. "ORCs are among the most bizarre and beautiful cosmic structures we've ever seen - and they may hold vital clues about how galaxies and black holes co-evolve, hand-in-hand."

Alongside the record-breaking ORC, two other extraordinary radio galaxies were uncovered: RAD J122622.6+640622, a nearly three-million-light-year-wide giant with a bent jet that forms a 100,000-light-year radio ring; and RAD J142004.0+621715, a 1.4-million-light-year system showing a ring and twin radio jets.

All three lie in dense galaxy clusters about 100 trillion times the mass of the Sun, where interactions between relativistic jets and million-degree plasma appear to sculpt these striking structures.

"These discoveries show that ORCs and radio rings are not isolated curiosities - they are part of a broader family of exotic plasma structures shaped by black hole jets, winds, and their environments," said co-author Dr Pratik Dabhade of the National Centre for Nuclear Research in Warsaw, Poland. "The fact that citizen scientists uncovered them highlights the continued importance of human pattern recognition, even in the age of machine learning."

Future observatories such as the Square Kilometre Array, together with optical surveys like DESI and LSST, are expected to reveal many more of these cosmic rings and shed light on their origins.

Research Report:RAD@home discovery of extragalactic radio rings and odd radio circles: clues to their origins

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