Odd radio circles are an extremely mysterious phenomenon in space. Now researchers know more about the giant ORCs.
Canberra – The universe is vast and far from fully explored. In this way, researchers are able to to discover previously unknown phenomena*. One of the currently most mysterious phenomena in space is called “ORCs” or “odd radio circles” (translated as “strange radio ring”). In 2020, a team led by astrophysicist Ray Norris from Western Sydney University discovered this phenomenon using the Australian radio telescope ASKAP. Referring to the apparition as “creepy glowing rings in the sky,” Norris recalls, “The rings were unlike anything we’d seen before, and we had no idea what they were.”
So far, the ORCs could only be discovered with radio telescopes, neither optical nor infrared wavelengths brought the mysterious rings to light and the researchers had no luck in the search for X-rays either. Only five of the strange objects are known so far, the theories surrounding them range from “galactic shock waves” to the assumption that they are the “maws of wormholes”. “People often want to explain their observations and show that they agree with the best of our knowledge. For me, it’s much more exciting to discover something new that contradicts our current understanding,” explains Jordan Collier, who is involved in a new study on the mysterious rings.
“Odd radio circles” (ORCs): Mysterious rings in space pose riddles
The ORCs “still puzzle us, but new data from South Africa’s MeerKAT telescope are helping us solve the mystery,” Norris writes on The Conversation portal. the studywhich the researchers wrote, was peer-reviewed and accepted for publication in the journal Monthly Notices of the Royal Astronomical Society.
The researchers who want to solve the mystery of the “odd radio circles” know from the new telescope data that there is a galaxy at the center of each mysterious ring that previously shone too weakly to be discovered. “The rings are most likely massive explosions of hot gas about a million light-years across, emanating from the central galaxy,” reports Norris. So the rings are huge – 16 times larger than our galaxy, the Milky Way.
Incidentally, based on the data from the MeerKAT telescope, these do not appear to be “rings” in the true sense of the word. Apparently, the ORCs are the edges of a spherical shell that surrounds the galaxy. The spheres look like rings because they appear brighter around the edges where there is more material along the line of sight — Norris likens it to soap bubbles.
Mysterious “Rings” in the Universe: How Did ORCs Form?
But what caused the mysterious, ring-shaped balls, how did the ORCs come about? The researchers assume that an explosion in the central galaxy triggered shock waves. According to the researchers’ theory, these shock waves would also have “swallowed up” other galaxies. But why did the explosion happen? The research team follows two approaches:
- Merger of two supermassive black holes: A huge amount of energy is released in the process, which would be sufficient to create an ORC.
- “Starburst” in a galaxy: In the process, millions of stars are suddenly formed from the gas in the galaxy. This event ejects hot gas from the galaxy, creating a spherical shock wave.
Universe: ORCs may have arisen from rare events
Both the Merging supermassive black holes* as well as star outbursts are rare events – which would explain why only five “odd radio circles” are known so far. “We know that ORCs are rings of faint radio emissions surrounding a galaxy with an active black hole at its center, but we don’t yet know what causes them or why they are so rare,” summarizes Norris.
The researchers are now hoping for an international telescope project that is currently in the making. The Square Kilometer Array (SKA) is a radio telescope project being built in South Africa and Western Australia. “There is no doubt that when the SKA telescopes are built, they will find many more ORCs and will be able to tell us more about the life cycle of galaxies,” Norris points out. Until the SKA is active, the researchers will continue to rely on the ASKAP telescopes in Australia and MeerKAT in South Africa to find out more about the “odd radio circles”. “The ORC mystery remains unsolved, and we still have much to learn about these mysterious rings in the sky,” concludes Norris. (tab) *fr.de and hna.de are offers from IPPEN.MEDIA.
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