What the study found
The study reports two intersecting radio shells, likely radio relics, around a compact galaxy group dominated by a massive elliptical galaxy. The authors identify this system as ORC J1841–6547, also known as ORC 6, and suggest that at least some odd radio circles are shock-energised relics.
Why the authors say this matters
The authors conclude that the system supports a formation scenario in which galaxy-merger shocks re-energise old radio lobes in the outskirts of galaxy groups. They say this helps explain how at least some odd radio circles may originate during the merger evolution of the brightest group galaxy.
What the researchers tested
The researchers studied 944 MHz radio continuum images from the Australian Square Kilometre Array Pathfinder (ASKAP) using Phased Array Feeds. They examined the radio structure around the compact galaxy group and compared it with available X-ray and other non-radio observations.
What worked and what didn't
The two shells appear as partial, edge-brightened rings with diameters of about 240 arcseconds, or roughly 720 kiloparsecs each. The north-western shell may be associated with an X-ray detection, while the weaker south-eastern shell has no counterpart at non-radio wavelengths; both shells resemble a pair of odd radio circles.
What to keep in mind
The paper presents a proposed formation scenario, not a confirmed one. The abstract does not describe detailed limitations beyond noting that only the north-western shell has a possible X-ray counterpart and that the south-eastern shell lacks non-radio emission.
- Two intersecting radio shells were discovered around a compact galaxy group.
- The system is described as likely radio relics and is called ORC J1841–6547, or ORC 6.
- The central galaxy is radio bright and shows signs of interactions.
- The north-western shell may have an X-ray counterpart, but the south-eastern shell does not.
- The authors propose galaxy-merger shocks as a possible source of the radio shells.