Astronomers observing a mysterious radio halo from the galaxy cluster Abell 1213 have uncovered something unexpected. While the radio signals themselves remain puzzling, they have allowed researchers to unveil the core of the galaxy cluster, right down to the central galaxy contained within.
Even more intriguing about the discovery is that the researchers found evidence of mergers between the galaxies with the cluster. The off-center nature of the radio halo has also provided scientists with quite a puzzle, as most radio signals of this sort act more in line with the gas and dust that make up the “intracluster medium.”
By utilizing data from the Sloan Digital Sky Survey (SDSS) and X-ray data from the XMM-Newton space telescope, astronomers were able to successfully map the structure and dynamics of the intracluster medium. Using that info, the astronomers were also able to determine that the mysterious radio halo is the size of around 1.66 million light-years but that it doesn’t follow the x-ray emissions in the area.
This has left several astronomers involved in the discovery baffled and searching for answers. They also detected a radio signal they believe to be the relic of a galactic merger between Abel 1213’s central galaxy and another galaxy. However, this relic does not appear to be the cause of the baffling radio halo. Instead, it’s just another piece of a much larger puzzle that scientists are trying to solve.
The discovery also led scientists to uncover that star formation in Abel 1213 is not tied to the edges of the galactic cluster. Instead, star-forming galaxies appear to be present throughout the cluster, which some believe may imply that the cluster forms when several different groups clump together. This does not appear to be responsible for the radio halo, either.
The astronomers recorded their findings in a paper currently available on arXiv. In order to determine exactly what is causing the mysterious radio halo, astronomers say we’ll need to observe the galactic cluster with deeper x-ray signals. Future observations of these enormous galaxy clusters with James Webb and other telescopes could provide more data about them.