An unusual double ring structure discovered in space by citizen scientists turns out to be a space rarity. Dr. Ananda Hota, lead author of the study, published in early October in the Monthly Notices of the Royal Astronomical Society, said the anomalous celestial object recorded by the radio telescope is a strange radio circle, one of the rarest and most mysterious objects in the Universe.
The strange radio circles, also known as ORCs, are likely made up of plasma-charged magnetized gas strongly influenced by magnetic fields, CNN reported, and they are so large that they contain entire galaxies at their centers. They span hundreds of thousands of light years and are often 10-20 times the size of our Milky Way galaxy. But they are also extremely weak and can usually only be detected by radio signals.
The newly discovered strange radio object, named RAD J131346.9+500320, is the most distant object known to date, located 7.5 billion light years from Earth, and the first to be discovered by civilian scientists. Additionally, this is only the second odd radio circle with two.
“ORCs are among the strangest and most beautiful cosmic structures we have ever seen, and they may hold important clues about how galaxies and black holes grow together,” said Ananda Hota, assistant professor at the University of Mumbai's Center of Excellence in Atomic Energy.
The strange radio circles were first discovered about six years ago, but their structure remains largely elusive.
Dr. Hota is the Director and Principal Investigator of the RAD@home Astronomy Collaborative, an online community open to anyone with a background in science. Astronomers train users to recognize patterns in weak, faint radio waves and analyze astronomical images, explains Ananda Hota.
The newly discovered strange radio circle has appeared in data from the Low Frequency Range (LOFAR) telescope, which includes thousands of antennas in the Netherlands and across Europe to create a large radio telescope. It is the largest and most sensitive radio telescope operating at low frequencies.
Although RAD@home participants were not specifically trained to look for strange radio circles, the unusual two-ring structure stood out, marking the first strange radio circle identified with LOFAR. The circles appear to intersect, which researchers think is because we see them from Earth, but it's more likely they're separated in space. The diameter of this pair is 978,469 light years. A light year is the distance light travels in one year, or 9.46 trillion km.
“This work shows how professional astronomers and citizen scientists can work together to push the boundaries of scientific discovery,” said Dr. Hota.
Astronomers have suggested that the strange radio circles could be wormhole openings, shock waves from black hole collisions or galaxy mergers, or powerful jets spewing energetic particles.
“We hypothesize that there was a massive explosion in the central galaxy. The resulting shock or blast wave may have activated the ancient magnetized plasma clouds, causing them to glow again like radio bells,” said Dr. Hota.
Ananda Hota explains that plasma clouds may have been first created by jets of matter released by the galaxy's supermassive black hole. He added that the new shockwave essentially clears up the “smoke” left behind by the galaxy's past activity.
Black holes do not directly consume stars, gas and dust. Instead, the matter will fall into a rotating disk around the black hole. As the debris spirals faster and faster, it becomes too hot. The strong magnetic field around the black hole helps guide these superheated, energetic particles away from the black hole in jets approaching the speed of light.
The team also discovered two more strange radio rings in two different galaxies, including one located at the end of a strong jet with a sharp bend, resulting in a radio ring about 100,000 light-years wide.
Both exotic radio rings are located in galaxies inside larger galaxy clusters, which means jets from their supermassive black holes interact with hot surrounding plasma, possibly helping to form radio rings, Hota noted.
Study co-author Dr. Pratik Dabhade, Associate Professor in the Department of Astrophysics at the National Center for Nuclear Research in Warsaw, commented: “These discoveries show that ORCs and radio rings are not separate rarities – they are part of a broader family of exotic plasma structures formed by black hole jets, winds and the environment.”
The discovery of the most distant strange radio ring to date effectively allows researchers to peer deep into the past. The team believes this phenomenon could be a way to record and preserve the ancient chaotic events that shaped galaxies billions of years ago.
Light from the radio ring traveled 7.5 billion years to reach Earth and could provide insight into the role of exotic radio rings in the evolution of galaxies over time, which is not widely known.
“By studying them at different cosmic times, we can begin to unravel how such bursts of energy affect the surrounding gas and promote or prevent star formation,” Hota said. “Our discovery pushes back the known age limit of ORCs to nearly half the age of the Universe, providing important clues to their origin and connection to the broader life cycle of galaxies.”
Many questions remain about the strange radio circles, including why astronomers only see them at such large sizes. Hota and Dabhade wanted to know whether the circles were expanding due to smaller, undetectable bubbles. And if radio circles are indeed the result of galaxy mergers or supermassive black holes, why aren't they noticed more often?
Answering these questions will require the help of citizen scientists and a new generation of telescopes, such as the square kilometer transcontinental complexes in South Africa and Australia.
Construction is currently underway and is expected to be completed in 2028. The complex will include thousands of dishes and up to a million low-frequency antennas to create the world's largest radio telescope.
Although these dishes and antennas will be located in two different parts of the world, they will form a telescope with a data collection area of more than 1 million square meters, allowing astronomers to observe the entire sky faster than ever before.
