Astronomers Captured a New Detailed Image of Odd Radio Circles (ORCs) Using the World's Most Capable Telescopes

Astronomers Captured a New Detailed Image of Odd Radio Circles Using the World's Most Capable Telescopes — Data from SARAO's MeerKAT radio telescope data (green) showing the odd radio circles, is overlaid on optical and near infra-red data from the Dark Energy Survey. © J. English (U. Manitoba)/EMU/MeerKAT/DES(CTIO)

Astronomers are getting closer to understanding a rare and unusual feature of the universe with its new detailed image captured by the South African Radio Astronomy Observatory's MeerKAT radio telescope. These objects are known as the odd radio cycles (ORCs). They are characterized by a smoky ring and hidden in deep space.

The international team of researchers has pulled into sharp focus the ORCs that were first revealed by CSIRO's Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope in 2020 that became objects of fascination in the field of astronomy. The new detailed image is published in the Monthly Notices of the Royal Astronomical Society.

(Photo : © J. English (U. Manitoba)/EMU/MeerKAT/DES(CTIO))
Data from SARAO's MeerKAT radio telescope data (green) showing the odd radio circles, is overlaid on optical and near infra-red data from the Dark Energy Survey.

A Little Back Story of the Odd Radio Circles (ORCs)

Way back in 2019, astronomer Anna Kapinska was trawling through the data from the ASKAP to search for unusual objects that the radio telescope found. According to CNet, she started pulling together a list of "WTF?" features, which included a new, unusual object that looks like a ghostly circle located about a billion light-years from Earth.

Researchers called them ORCs, describing them as a remnant of a supernova. Astronomer Emil Lenc also looked through similar objects and flagged his findings with astrophysicist Ray Norris of CSIRO. Despite looking like a remnant of a star that has exploded, researchers said that the data did not fit.

"Fairly quickly, we realized this is really something quite different," CNet quoted Norris. "It's something quite new."

These ORCs are only visible when viewed using radio telescopes, such as in X-ray telescopes like NASA's Chandra or the infrared wavelengths like the James Webb Space Telescope.

But since then, astronomers have described and found five different ORC from similar regions in space. Today, the ORC1 that Lenc first spotted has come into focus in the new paper from CSIRO.

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Theories That Describe Causes of ORCs

According to CSIRO's news release, there are three leading theories on ORCs' origin. First, ORCs could be remnants of massive explosions at the center of their host galaxy, which happens when two supermassive black holes merge. Secondly, ORCs could be powerful jets of energetic particles from the center of their host galaxy. Third, ORCs might be the result of the starburst termination shock from the star nursery in the host galaxy.

The image taken using the MeerKAT radio telescope is a compilation of images that Dr. Jordan Colier of the Inter-University Institute for Data-Intensive Astronomy collected. He said it was exciting to discover something new that defies current understanding.

As seen in the image, the ORC1 has enormous rings that are about a million light-years across and are 16 times bigger than the Milky Way galaxy. However, it remains hard to detect without using radio telescopes.

For now, ASKAP and researchers operating MeerKAT are working together to find and describe other OCRs quickly and efficiently. Professor Elaine Sadler, the Chief scientist at CSIRO's ASKAP, said that nearly all astronomy projects today are made possible with international collaboration in which both teams consist of people involved with the available technology, particularly with radio telescopes.