Citizen scientists have found several new “odd radio circles<" or ORCs, in distant, enormous galaxy clusters — and through their discoveries, scientists are learning more about how these huge ring-like structures form. Intriguingly, these ORCs seem to be related to radio jets blasting out from each of the galaxies. As the jets spiral around magnetic-field lines, they produce radio emission in the form of synchrotron radiation. At the end of this diverted jet is a huge ring of radio emission, 100,000 light-years across. In the other giant radio galaxy, RAD J142004.0+621715 which has a 1.4-million-light-year-wide emission, one of the jets is also found to end in a large ring of radio emission.
The formation of these massive ring-like structures is being better understood thanks to the discoveries made by citizen scientists who have discovered a number of new “odd radio circles,” or ORCs, in far-off, massive galaxy clusters.
Just six years ago, in 2019, Anna Kapinska of the National Radio Astronomy Observatory discovered ORCs while looking through observations from the Australian sq\. Kilometre Array Pathfinder (ASKAP). The size of ORCs can be up to 50 times that of our Milky Way galaxy, which is roughly 100,000 light-years across. Only radio telescopes are able to detect their ghostly structures, making them invisible at optical, infrared, and X-ray wavelengths.
The study’s lead researcher, Ananda Hota of the University of Mumbai, said in a statement that ORCSs are “among the most bizarre and beautiful cosmic structures we’ve ever seen, and they may hold vital clues about how galaxies and black holes co-evolve, hand-in-hand.”.
These three new findings imply that ORCs might be more widespread than astronomers previously believed, even though there have only been eight ORCs positively identified in the entire universe to date.
The team’s discovery was made possible by citizen scientists searching through data on the RAD@home Astronomy Collaboratory, which Hota founded and is India’s first citizen science platform.
LOFAR, the Low Frequency Array of radio antennas located throughout Western Europe with its center in the Netherlands, then verified the radio rings.
One of the recently found ORCs is actually two massive, expanding rings that are 978,000 light-years across. They are embedded in a diffuse radio emission haze that is 2.6 million light-years across. This haze is connected to a giant radio galaxy known as RAD J131346.9+500320, whose numbers correspond to its right ascension and declination coordinates on the celestial sphere, respectively. It is the most powerful and distant ORC system discovered to date, with a distance of roughly 7 billion light-years (a redshift of 0.94). This is only the second time that twin ORCs have been discovered. According to Hota’s team, the rings are remnants of a past galaxy outburst that are being reenergized by a superwind of radiation erupting from either a starburst or black hole activity in the center of RAD J131346.9+500320.
About 1–3 billion light-years away (redshifts of approximately 0–1), two additional large, ring-shaped, radio-emitting structures were discovered to be connected to giant radio galaxies a little closer to home. Remarkably, these ORCs appear to be connected to radio jets that are exploding from every galaxy. Radio jets are strong charged particle beams created by energy near a supermassive black hole that lurks at the center of an active galaxy. Synchrotron radiation, a type of radio emission, is created as the jets spiral around magnetic-field lines.
One of the radio jets is bending sideways and flowing back towards the galaxy in one of the galaxies, described as RAD J122622.6+640622, which has diffuse radio emission over a genuinely enormous 3 million light-years. A massive, 100,000 light-year-wide ring of radio emission can be seen at the end of this diverted jet.
One of the jets in the other giant radio galaxy, RAD J142004.0+621715, which has an emission that is 1 point 4 million light-years wide, is also discovered to terminate in a sizable ring of radio emission.
Common to all three galaxies is their location within massive galaxy clusters that are encased in the intra-cluster medium, a dense fog of hot plasma. The radio rings and jets appear to be shaped by interactions between the radio jets and the intra-cluster medium, a dense fog of hot plasma that surrounds galaxy clusters, especially in the case of the last two galaxies.
Pratik Dabhade of the National Center for Nuclear Research in Warsaw, Poland, said in the statement, “These findings demonstrate that ORCs and radio rings are not isolated curiosities.”. “Black hole jets, winds, and their surroundings have shaped a wider family of exotic plasma structures, of which they are a member. “..”.
The results are a victory for human data analysis and citizen science in the face of an increasingly A-dominated world. Me. machine learning that is removing people’s access to discoveries.
According to Dabhade, “the fact that citizen scientists discovered them emphasizes the ongoing significance of human pattern recognition, even in the age of machine learning.”.
It is anticipated that the sq\. Kilometre Array, a massive radio telescope network based in Australia and South Africa that will go online in the early 2030s, will discover many more ORCs in the future.
