Scientists working with South Africa’s MeerKAT telescope have studied the elliptical galaxy WISEA J021912.43-050501.8. There they found a remarkable radio ring. Such structures have been discovered more and more often in recent times.
Scientists’ new discovery
Using the MeerKAT telescope, astronomers have discovered a new odd radio circle that seems to be associated with an elliptical galaxy known as WISEA J021912.43-050501.8. The discovery, which may help us better understand the nature of this mysterious radio emission phenomenon, is reported in a paper published on November 26 on the arXiv preprint server.
So-called odd radio rings (ORCs) are mysterious giant rings of radio waves whose origin is still unexplained. They are usually observed as extragalactic circles with a steep radio emission spectrum, with no corresponding emission at other wavelengths than the host galaxy. To date, only a few such objects have been clearly identified as ORCs.
Now a team of astronomers led by Ray P. Norris of the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) reports the discovery of another ORC. The discovery was made as part of the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE), a deep radio survey being conducted with the MeerKAT telescope.
“We present the discovery of a new odd radio circle (ORC J0219–0505) in 1.2 GHz radio continuum data from the MIGHTEE survey taken with the MeerKAT,” the researchers wrote in the paper.
Strange radio ring ORC J0219-0505
The newly found ORC, designated ORC J0219-0505, was identified as a ring of radio emission with a bright edge surrounding a compact radio source in the center. This ring is filled with faint diffuse radiation with hints of some structure. In addition, the observations also revealed a faint diffuse emission extending to the southeast of the ring.
According to the study, the parent galaxy of the new ORC is the massive elliptical galaxy WISEA J021912.43-050501.8, which shows elongated features visible in optical and infrared images. Such elongated outlines are characteristic of a perturbation due to merger or interaction, leading to the suggestion that ORC J0219-0505 may be an envelope of radio emission that is formed from electrons charged by the spherical shock from merging galaxies.
Dimensions of ORC J0219-0505 and research perspectives
ORC J0219-0505 has a diameter of 35 arc seconds, corresponding to 371,600 light-years (assuming the redshift of the host galaxy is 0.196), and its width is about 107,500 light-years.
The researchers note that ORC J0219-0505 is much smaller and weaker than previously found single ORCs. They added that the discovery of this galactic center in a deep but relatively small radio survey indicates that there is a fainter population of galactic centers that has yet to be detected with MeerKAT or other radio telescopes.
The authors of the paper plan further studies of ORC J0219-0505, which will focus on its morphological features, polarization and spectral properties. Such a study may be important to better understand the process that generates ORC.
Provided by phys.org
