Utilizing the LOw Frequency ARray (LOFAR), astronomers have explored PSZ2 G099.86+58.45, one of the thickest cluster of galaxies known so far. The research revealed the presence of a radio halo on this cluster, making it probably the most distant such features ever found. The discovering is detailed in a paper published July 24 on arXiv.org.
With the capability of acquiring deep, high-resolution, high-fidelity, and low-frequency radio pictures, LOFAR is an excellent tool to review radio halos at low frequencies with unparalleled detail and responsiveness. So a crew of astronomers led by Rossella Cassano of Institute for Radio Astronomy of Bologna, Italy, operated LOFAR for the observations of the galaxy clusterPSZ2 G099.86+58.45.
At a redshift of roughly 0.62, PSZ2 G099.86+58.45 (PSZ2G099 for brief) is a massive and scorching galaxy cluster of about 684 trillion solar masses. Observations have proven that the cluster resides in a high-density environment, about six occurrences denser than the average Lambda cold dark matter model prediction at this redshift.
Cassano’s group investigated PSZ2G099 with LOFAR as a part of the LoTSS (LOFAR Two-meter Sky Survey) program. Additionally, they carried out follow-up observations of the cluster utilizing the Karl G. Jansky Very Large Array (JVLA). All in all, the observational campaign resulted within the detection of a radio halo on this object.
Notably, LOFAR observations at medium decision revealed extended diffuse emission on the center of PSZ2G099, with dimensions measured at round 3.9 by 1.95 light-years. As anticipated, this emission could be very faint at higher frequencies and therefore was barely detected by JVLA.