by Astronomers have for the first time imaged a strange circle in space in high resolution as they try to figure out how these mysterious structures form.
The enigmatic shapes, known as odd radio circles (ORCs), were first spotted in 2019 in images from Australia’s Square Kilometer Array Pathfinder (ASKAP) radio telescope. Consisting of 36 colossal dishes in Western Australia, ASKAP maps the entire night sky in radio waves and begins to see circles at various points.
Each circle appears to be several billion light-years away and possibly a few million light-years across. Individual ORCs appear to have galaxies at their centers, but are strangely only visible in radio waves.
More information is coming in now. The South African Radio Astronomy Observatory’s MeerKAT radio telescope array has acquired a new detailed look at one of the circles, nicknamed ORC 1 (“Odd Radio Circle 1”). The image was shared in a statement on Tuesday (March 22).
While the research is still ongoing, the astronomers say such images will eventually allow them to narrow down how these radio structures are formed and better fit into ORC evolution with the universe as a whole.
Astronomers have only found the ORCs at radio wavelengths, making them even more mysterious since the objects don’t show up in other surveys using optical, X-ray, or infrared telescopes.
There are currently three theories as to how ORCs arise. For one, they could represent a gigantic explosion at the center of their host galaxy, on the scale of two supermassive black holes merging.
Other possibilities include ORCs, which are jets of energetic particles emanating from the center of the galaxy, or a starburst “termination shock” produced as stars form.
The team admitted in a statement that more detailed radio surveys are needed to learn more, but added that they are excited to discover something new in the sky.
“We know that ORCs are rings of faint radio emissions surrounding a galaxy with a highly active black hole at its center, but we don’t yet know what causes them or why they are so rare,” explained lead author Ray Norris, a data Scientists and astrophysicists from Western Sydney University and the Commonwealth Scientific and Industrial Research Organisation.
The team hoped to gain access to “even more sensitive radio telescopes” like the Square Kilometer Array (SKA) Observatory. Construction of the world’s largest radio observatory began in 2021. First light is expected in 2027.
The range of dishes is positioned at two locations. The SKA mid-array in the Karoo desert in South Africa will use 197 mid-band dishes. The SKA low array includes 131,072 antennas located north of Perth, Australia to listen for lower frequency bands.
A paper based on the research is expected to be uploaded to the Royal Notices of the Astronomical Society shortly. A pre-release of the paper is available on Arxiv.
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