(ORDO NEWS) — Australian scientists have discovered several mysterious ring structures emitting in the radio frequency range, but have not been able to understand how far away they are, what size and where they come from in space.
Fast radio bursts – unusually powerful pulses that appear and almost instantly disappear in seemingly random areas of the sky – have long remained one of the greatest mysteries of astronomy. However, it seems that the work of recent years removes this issue, making it possible to associate the occurrence of such radio bursts with distant magnetars – rapidly rotating neutron stars with an extremely powerful magnetic field. But in place of these impulses a new mystery comes.
In the fall of 2019, Australian scientists conducted a trial analysis of data collected by the ASKAP radio interferometer as part of a new Evolutionary Map of the Universe (EMU) survey. In the images they obtained, they noticed a pair of strange ring-shaped structures emitting in the radio frequency range. After making sure that their appearance was not associated with an error in the collection or processing of data, astronomers began to look closely at the images with particular attention and since then have discovered a couple of similar rings.
Anna Kapinska and her colleagues called these structures “strange radio rings,” Odd Radio Circles (ORCs). Scientists write about the first observations in a new article accepted for publication in the journal Publications of the Astronomical Society of Australia and already available in the ArXiv.org online preprint library. The authors note that so far we can say almost nothing definite about them.
Neither the distance to the rings, nor, therefore, their magnitude is known: they can be in our Galaxy and gain a few light years across or far beyond its limits, and then reach a diameter of millions of light years. ORCs do not emit in the optical range. So far, scientists have only been able to discard some of the most obvious possibilities for explaining ORCs.
They are too far away from visible star clusters to be unlikely to be created by supernova explosions. It was not possible to connect the rings with galaxies in which active star formation is taking place. And they are unlikely to arise from supermassive black holes ejecting matter with powerful jets: otherwise ORCs would not have such a round shape. For the same “geometric” reason, they cannot be the result of gravitational lensing of radio emission from more distant sources. “Finding such a riddle is the dream of any astronomer,” writes one of the authors of the find, a professor at the University of Western Sydney Ray Norris.
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