'Ghostly circles' appearing in the universe puzzles astronomers, what are they?

A recent report by Space.com has revealed some shocking details about the universe. It claims that in September 2019, astronomers came across interesting objects while browsing through new radio astronomical data of the Australian SKA Pathfinder Telescope. Astronomers noticed weird shapes that couldn’t be fit easily to any known type of object. The astronomers dubbed these objects as ORC or odd radio circles for time being. But they are also calling them 'ghostly circles' based on their appearance. Read on to know more.

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Astronomers find Ghostly Circles in the universe

The report by Ray Norris, an astrophysicist and science communicator, based at the CSIRO Australia Telescope National Facility, and Western Sydney University, has been published in the Op-Ed section of space.com. The astrophysicist reveals that his colleague Anna Kapinska had brought these weird-looking bubbles to the notice of other scientists. Kapinska came across these images while examining the new images from the pilot observations for the Evolutionary Map of the Universe (EMU) project, made with CSIRO’s revolutionary new Australian Square Kilometre Array Pathfinder (ASKAP) telescope.

Source: Dark Energy Survey.org

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What are these Odd Radio Circles?

Norris reveals in his article that at first astrophysicists suspected an imaging artefact, perhaps generated by a software error. However, upon further probing it became clear that they were real, but it still unclear how big or far away they are. There is a high possibility that they could be objects from our galaxy, perhaps only a few light-years across. But there is also a chance that they could be far away in the Universe and maybe millions of light-years across. When astronomers looked at the images carefully, they deduced that the rings of radio emission were probably caused by clouds of electrons, but why don’t we see anything in visible wavelengths of light? The mystery behind these ghostly circles got even more puzzling. 

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Could they be supernova remnants?

There might be a chance that these circles are supernova remnants, which are the clouds of debris left behind when a star in our galaxy explodes. But Norris says that the astrophysicist has ruled supernova out as they are far from most of the stars in the Milky Way and there are too many of them. They cannot be the rings of radio emission that we sometimes see in galaxies undergoing intense bursts of star formation. This is because astronomers are unable to see any underlying galaxy that would be hosting the star formation.

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Lastly, there is a chance that they could be Einstein rings, in which radio waves from a distant galaxy are being bent into a circle by the gravitational field. But then the ORCs are too symmetrical, and no cluster is visible at the centre. From the handful of data that his available about the ORCs, astronomers have estimated that there are about 1,000 ORCs in the sky. However, only more research could answer the puzzling questions that ORCs have posed on the scientific community.