Something unusual is lurking in the depths of space: astronomers have discovered four weak objects that are very circular and brighter at their edges at radio wavelengths. And they are different from any class of astronomical object that has ever been seen before.
The objects, which look like distant circular islands, have been called strange radio circles or ORCs because of their shape and general peculiarity. Astronomers don̵
In a new article detailing the discovery, astronomers offer several possible explanations, but none fits the bill for all four new ORCs. After excluding objects such as supernovas, star-forming galaxies, planetary nebulae, and gravitational lenses – a magnification effect due to the bending of space-time by nearby massive objects – the astronomers speculate, among other things, that the objects could be shock waves left by some are an extragalactic event or possibly activity of a radio galaxy.
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“”[The objects] could indicate a new phenomenon that we haven’t really investigated yet, “said Kristine Spekkens, astronomer at the Royal Military College in Canada and at Queen’s University, who was not involved in the new study.” It may also be an extension of a previously known class of objects that we have not been able to explore. “
Spekkens added that the objects could also be caused by various phenomena. All four ORCs are bright at radio wavelengths, but invisible in visible, infrared and X-rays. However, two of the ORCs have galaxies at their center that are visible at visible wavelengths, suggesting that these objects may have been formed by these galaxies. Two ORCs also appear to be very close together, which means that their origins could be linked.
Astronomers discovered three of the objects while imaging the night sky in radio frequencies. This was part of a pilot study for a new project called Evolutionary Map of the Universe (EMU). The EMU pilot used the Australian Square Kilometer Array Pathfinder (ASKAP) from July to November 2019. This radio telescope array uses 36 antennas that work together to observe a wide-angle view of the night sky. They found the fourth ORC in archive data collected by the Giant MetreWave Radio Telescope in India. This helped the astronomers to confirm the objects as real and not as an anomaly caused by problems with the ASKAP telescope or the way the data was analyzed.
Since only four of these special objects have been discovered so far, astronomers cannot yet determine the true nature of these structures. But the EMU survey is just beginning and astronomers expect it to reveal more unusual objects.
By combining the ability to see weak radio objects with a wide view, the survey is uniquely positioned to find new objects. WWU scientists have predicted that the project will find around 70 million new radio objects – an expansion of the current catalog by around 2.5 million.
“This is a really nice indication of the shape of things that can be expected in radio astronomy in the next few years,” Spekkens told Live Science. “History shows us that when we open a new one [avenue of looking at] Space to explore … we always find new and exciting things. “
The paper, which is available on the arXiv preprint website, has been submitted for publication by Nature Astronomy, where it is still under review.
Originally published on Live Science.