The Australian Square Kilometer Array Pathfinder was utilized to scan the heavens for radio waves.
(Image: © CSIRO)
There’s something unusual lurking outside in the depths of space: Astronomers have discovered four faint items that at radio wavelengths are exceptionally circular and brighter along their borders. And they’re unlike any class of object observed before.
The objects, which seem like remote ring-shaped islands, have been dubbed odd radio circles, or ORCs, for their shape and total peculiarity. Astronomers do not yet know exactly how far away these ORCs are, but they could be linked to remote galaxies. All things were found away in the Milky Way’s galactic plane and are approximately 1 arcminute across (for contrast, the moon’s diameter is 31 arcminutes).
At a new paper detailing the discovery, the astronomers provide many possible explanations, but not one quite matches the bill for all four new ORCs. After ruling out objects such as supernovas, star-forming galaxies, planetary nebulas and atmospheric lensing — a magnifying effect due to the bending of space-time by nearby massive objects — among other things, the astronomers speculate that the objects might be shockwaves left from some extragalactic occasion or possibly activity from a radio galaxy.
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“[The objects] may well point to some other phenomenon that people have not actually probed however,” said Kristine Spekkens, astronomer at the Royal Military College of Canada and Queen’s University, who was not involved with the new study. “It might also be that these really are an extension of some previously known class of objects that we haven’t been able to explore.”
Spekkens added that the items could also be caused by various phenomena. These four ORCs are glowing at radio wavelengths but undetectable in visible, infrared and X-ray mild . But two of the ORCs have galaxies in their center which can be found. Two ORCs also seem to be close together, meaning their origins could be linked.
Astronomers spotted three of those things while mapping the night sky in radio frequencies, either a portion of a pilot survey for a new project called the Evolutionary Map of the Universe (EMU). The EMU pilot utilized the Australian Square Kilometer Array Pathfinder, or ASKAP, from July to November in 2019. This radio telescope range uses 36 dish antennas, which work together to observe a wide-angle view of the nighttime skies. The fourth ORC was found by them in archival data gathered by the Giant MetreWave Radio Telescope in India. This helped the astronomers to verify the manner in along with the objects as real, rather than some anomaly brought on by problems with the ASKAP telescope.
With just four of those peculiar objects found so far, the astronomers can not yet tease the true nature of these structures. However, the EMU poll is just starting, and astronomers anticipate it to show objects that are odd.
By combining an ability to see faint radio items with a wide gaze, the survey is uniquely positioned to find new objects. EMU scientists have predicted the project will find about 70 million new radio items —- expanding the current catalog of some 2.5 million.
“That is a very nice sign of the shape of things to come in radio astronomy in another couple of years,” Spekkens informed Live Science. “History shows us that when we start up a fresh [avenue of looking at] space to research… we constantly discover new and exciting items.”
The newspaper, which will be available on the preprint site arXiv, has been submitted for publication to the journal Nature Astronomy, in which it’s still under review.
Originally printed on Live Science.