Australian astronomers have detected a series of inexplicable signals that they believe could be “a new class of astronomical object.”
A team of international researchers at the Australian Square Kilometre Array Pathfinder (ASKAP), in the continent’s Western region, has dubbed the objects “odd radio circles,” or ORCs.
Led by astrophysicist Ray Norris of Western Sydney University, the scientists shared their findings on arXiv, an open-access scholarly articles archive, while their report awaits peer review for publication into the journal Nature Astronomy.
Their study describe four ORCs, which appear as glowing orbs, three of which have distinct, bright rings around the circular object — and ruled out several possible explanations for their existence.
“Circular features are well-known in radio astronomical images, and usually represent a spherical object such as a supernova remnant, a planetary nebula, a circumstellar shell, or a face-on disc such as a protoplanetary disc or a star-forming galaxy,” they wrote in their report.
“They may also arise from imaging [artifacts] around bright sources caused by calibration errors or inadequate deconvolution. Here we report the discovery of a class of circular feature in radio images that do not seem to correspond to any of these known types of object or [artifact], but rather appear to be a new class of astronomical object,” they explained.
The ORCs were first spotted in 2019, during a survey of the night sky which lasted from July to November for the Evolutionary Map of the Universe (EMU). They explain that one undefined object could be considered a glitch, but three or more suggests a pattern. The “radio quiet zone” surrounding ASKAP makes the likelihood of an instrumental quirk less probable, according to the Live Science report. Furthermore, archival data from the Giant MetreWave Radio Telescope in India confirmed the presence of one of the ORCs discovered at ASKAP.
“[The objects] may well point to a new phenomenon that we haven’t really probed yet,” said Kristine Spekkens, from the Royal Military College of Canada and Queen’s University.
“It may also be that these are an extension of a previously known class of objects that we haven’t been able to explore,” Spekkens, who was not involved in the study, told Live Science on Wednesday. She also noted that the imaging revealed galaxies at the center of two of the four ORCs, which may indicate that they were formed by those galaxies.
Scientists for the EMU project have said that upcoming studies of radio wavelengths could uncover some 70 million new radio objects, adding to their current log of just 2.5 million such phenomena.
“This is a really nice indication of the shape of things to come in radio astronomy in the next couple of years,” added Spekkens. “History shows us that when we open up a new [avenue of looking at] space to explore … we always find new and exciting things.”