Astronomers have snapped a close-up of a rare and mysterious space object, prompting a renewed push to discover its origin. Individual radio circuits (ORCs) are giant rings of radio waves. Only five people were ever seen, never seen in such stunning detail.
The image of ORC J2103-6200, also called ORC1, was taken by the MeerKAT High Resolution Radio Telescope in South Africa, which has provided researchers with unprecedented information about these rare phenomena. Details were reported in a preliminary version published on arXiv1 This week, it will be published in Monthly Notices of the Royal Astronomical Society2.
“This discovery will start new scientific research among astronomers,” says Alice Pacito, a radio astronomer at the National Autonomous University of Mexico in Mexico City.
New MeerKAT radio data shows that the ORC’s large outer circle is probably across more than a million light-years across, ten times the diameter of the Milky Way, with a series of smaller rings inside. “It really reminds me of a Faberge egg or a soap bubble,” says Barbel Koribalsky, a radio astronomer at the Commonwealth Scientific and Industrial Research Organization in Sydney.
The first three ORCs, including ORC1, were discovered using the Australian Square Kilometer Pathfinder (ASKAP) telescope in 2019. A fourth was identified in archival data from India’s Giant MetreWave Radio Telescope in 2013, and a fifth was discovered by Koribalski in ASKAP’s most recent data of the year. Past3. At the center of most of the ORC is a galaxy, which astronomers suggest may have something to do with their creation. Also baffling scientists is the fact that ORCs have only been spied on radio waves and have not been detected by optical or X-ray telescopes.
The researchers proposed three theories to explain the origin of ORCs. The first is that they consist of a shock wave from the center of their galaxy, similar to what happens when two supermassive black holes merge.
The second theory is that it is caused by the activities of an active galactic nucleus, with radio jets spewing out particles to create an ORC shape. The third theory is that ORCs are shells created by a starburst at the center of their galaxies. “Like a detective, we’re gathering more and more evidence about what this thing could be,” Koribalski says.
ORCs detected so far using ASKAP, due to their huge field of view, have been found. Radio telescopes can generally view an area the size of the Moon, while ASKAP can scan areas a hundred times larger. Once ORC1 was detected by ASKAP, MeerKAT was used to examine it in more detail because its higher resolution provides a clearer radio image.
“The ORC project is a great example of the intelligent use of MeerKAT by its users, exploiting its strengths: ASKAP monitors vast expanses of the sky and can detect relatively rare types of objects; said Fernando Camilo, chief scientist at the South African Radio Astronomy Observatory in the Cape. Town, in a press release, “MeerKAT can then proceed to study it in more detail.” The observatory built and operated MeerKAT.
Koribalsky says that other high-resolution radio telescopes around the world will likely soon be pointing toward these objects, especially once the next generation of these instruments comes online in the next few years. This array includes the Square Kilometer Array, which will have thousands of antennas across two locations in Australia and South Africa, and the next generation Very Large Array in the United States.
“Without a doubt, radio astronomers will be drawn to this new type of object,” says Basito.
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