Mysterious ORCs (private radio circuits) in space are still our best view

Enlarge / Data from SARAO’s MeerKAT radio telescope shows individual radio circuits overlapping in adjacent optical and infrared data from a dark energy survey.

J. English (U. Manitoba) / EMU / MeerKAT / DES (CTIO)

Astronomers have been confused about the nature and origin of rare and mysterious radio circuits in space since the objects were discovered in 2019. Today, the Mirkat High Definition Radio Telescope in South Africa captured the circuits in detail . Some useful advice on this rare event. The image and related analysis appeared on the front axle on arXivAnd this paper has been approved for publication in the monthly announcements of the Royal Astronomical Society.

The invention was born Evolutionary map of the universe (EMU), its purpose takes a questionnaire radio sources in the sky. Many years ago, astronomer Ray Norris worked at the University of Western Sydney CSIRO Australia, the EU project was expected to bring unexpected innovations. He called them “WTF”. Norris accepted the 2020 paper Conversationally, we can expect these results to emerge from the data-heavy machine learning analysis. “But these discoveries were made with good ancient vision,” he writes.

He is holding a pair of Anna Kapinska glasses, an astronomer at the National Radio Astronomy Laboratory (NRAO). Scanning through new radio astronomy data collected by CSIRO’s Australian Square Kilometer Array (ASKAP) telescope, Kabinska noticed several strange patterns. After Norris was nominated, they were potentially named WTF. One, according to Norris, is “an image of a ghostly circle of radio broadcasts suspended in space, like the Cosmic Smoke Ring.”

Enlarge / (Left) Data from the ASKAP radio telescope provided by the ORC1 Scientific Research Group (EMU) original discovery of the evolutionary map of the universe. Continuous monitoring of ORC1 by the Mirgate radio telescope (right)

Scalable map of the universe

Soon, other members of the team discovered two different circuit fluctuations, which they called individual radio circuits (ORCs). The fourth ORC has been identified as archival data from India’s giant MetreWave radio telescope, and the new fifth ASKAP data was discovered last year. Many objects can be ORCs. Based on this, the committee estimates that there could be a total of 1,000 ORCs.

When Norris And others. At first, the bubbles were thought to be imaging artifacts, but data from other radio telescopes actually confirmed that they were a new kind of astronomical object. They are not displayed on standard optical or infrared and x-ray telescopes – only on the radio spectrum. Astronomers suspect radio emissions from electron clouds. But that does not explain why ORCs are not represented at other wavelengths.

All ORCs confirmed so far have a galaxy at their center, suggesting this may be a factor in their formation. It is very large, about 1 million light-years in diameter, much larger than our galaxy, the Milky Way. “ORCs are rings of faint radio emissions around a galaxy that we know has a very active black hole at their center, but we still don’t know what causes them, or why they are so rare. ” Norris said.

The lines around the edge of the ORC indicate the direction of the magnetic field.  Such a circular magnetic field indicates that it has been compressed by a shock wave coming from the central galaxy.
Enlarge / The lines around the edge of the ORC indicate the direction of the magnetic field. Such a circular magnetic field indicates that it has been compressed by a shock wave coming from the central galaxy.

Larry Rodnick / Mirkot

Astronomers have come up with many possibilities for what the objects look like. It could be a supernova remnant or Einstein’s rings. Alternatively, although ORCs are usually much more rounded than the clouds that result from this phenomenon in radio galaxies, they can be caused by streams of electrons emanating from near a very large black hole. A highly speculative plan has been put forward that ORCs might actually be “shared” wormholes.

According to Norris, ASKAP is ideal for exploring large areas of the sky, while MeerKAT is designed to magnify any object of interest, so the two classes of telescopes complement each other. This latest radio image from MeerKAT shows several small rings within a large outer circle. Miragade also mapped the polarity of the radio wave, detecting a magnetic field at the edge of the sphere. This is similar to an eruption in the central galaxy.

“We can now see that each orc is centered on a galaxy, which is much darker than previously discovered,” Norris wrote. New article In Conversation. “The circles often erupt a million light-years from the central galaxy, and they are massive explosions of hot gas. Instead of balls, they look like rings, shining around the edges of the ball, like a bubble of soap in my opinion.

Fifteen of the Mirkat radio telescope's 64 meals under the starry skies of Karu, South Africa.
Enlarge / Fifteen of the Mirkat radio telescope’s 64 meals under the starry skies of Karu, South Africa.

Radio astronomy laboratory in South Africa

What caused the explosion that led to the formation of the ORC? The new data is sufficient to rule out all but three possibilities. First, ORCs are the result of a shock wave from the center of the galaxy that may come from the merger of two large black holes. Alternatively, it may be the result of radio jets emitting particles from active galactic nuclei. Finally, ORCs can be galactic bombs (“termination shock”), which create a spherical shock wave when hot gas is emitted from the galaxy.

Additional data is needed to determine which of these assumptions is correct. Norris hopes that a larger group of radio telescopes, called the Square Kilometer Array (SKA), will be operational by 2028, and that SKA will find more ORCs to learn more about the life cycle of galaxies. Additional tracking data can help astronomers identify oddly curved radio emission strands lurking in the outer ring.

Meanwhile, many astronomers are faced with a new cosmic mystery to solve. “People often want to explain their observations and show that they have the best information we have.” Co-author Jordan Collier said: International University Institute for Data-Intensive Astronomy. “For me, finding something new is so exciting, it’s beyond our current understanding.”

DOI: Royal Astronomical Society Monthly Announcements, 2022. 10.1093/manras/stac701 (About DOIs)

Artist’s impression of private radio circuits emanating from the center of the galaxy.

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