A team of European astronomers investigated the galaxy cluster known as PSZ2G113.91-37.01 (or G113 for short) using ESA’s XMM-Newton satellite and the Low Frequency Array (LOFAR). The results of the surveillance campaign are presented in a paper published on the preprocessing server on October 5. arXivThis will shed more light on the properties and nature of the cluster.

Galaxy clusters contain up to a thousand galaxies bound together by gravity. They are formed by the accumulation of mass and the collapse of smaller substructures and are the largest known gravitationally bound structures in the universe. Therefore, they can serve as excellent laboratories for studies of galaxy evolution and cosmology.

Discovered in 1999, G113 is a galaxy cluster with a redshift of 0.371. It has a mass of approximately 758 trillion solar masses, a radius of approximately 4 million light-years, and is known to contain a radio halo and two radio remnants. G113 is an understudied cluster that has not yet been observed by any large X-ray satellite.

A group of astronomers led by Maria Giulia Campitiello of the University of Bologna in Italy set out to change that. As part of the Cluster HERitage project XMM-Newton: Mass assembly and thermodynamics at the edge of structure formation (CHEX-MATE) they studied G113 in X-rays. Their work was supported by images from the LOFAR Two-Meter Sky Survey-Data Release 2 (LoTSS-DR2).

Observations revealed that G113 was undergoing a merger process along its north-south axis and confirmed the presence of a radio halo and two radio remnants in the central region. It turns out that the remnants are perpendicular to the fusion axis, one in the northern region and the other in the southern region.

Based on X-ray data, astronomers discovered a gap in surface brightness in G113’s northern region. Further analysis of this gap allowed them to classify it as a cold front. Additionally, the temperature map also revealed the existence of another cold region located in the southern part of the cluster.

The study found that the halo region has a mean spectral index of approximately -1.15 and a corresponding standard deviation of 0.23. The results also show a flattening of the spectral profile in the northern part of the northern remnant; This could be caused by particles accelerated by the outward moving shock.

In addition, the researchers performed a point-by-point analysis of X-ray and radio emission in both the halo and northern remnant regions of G113 and found a strong correlation for the halo and an anti-correlation for the remnant. The result is consistent with previous research. To summarize, the authors of the article recommend further observations to determine the physical processes that create this correlation and anticorrelation.