New Catalogue of X-ray Galaxy Groups Released

A new all-sky catalogue of X-ray detected galaxy groups, named AXES-2MRS, has been introduced by researchers H. Khalil, A. Finoguenov, E. Tempel, and G. A. Mamon. This catalogue is based on the identification of large X-ray sources found in the ROSAT All-Sky Survey (RASS) and the Two Micron Redshift Survey (2MRS) Bayesian Group Catalogue. The study aims to analyze the basic properties of these galaxy groups to understand the impact of different selection criteria on their characteristics.

The AXES-2MRS catalogue provides detailed X-ray properties by matching its data with archival observations from XMM-Newton, enhancing the understanding of galaxy group dynamics. The researchers focused on analyzing temperature and density to the lowest overdensity accessible by the data, which allowed them to obtain hydrostatic mass estimates and compare these with the velocity dispersions of the groups.

A significant finding from this research is the large variation in the central mass to virial mass ratios for galaxy groups in the XMM-Newton subsample. This variation may indicate either a substantial non-thermal pressure affecting X-ray mass measurements or a diversity of halo concentrations influencing the X-ray properties of these groups. Unlike previous catalogues that primarily sampled high-concentration groups, the AXES-2MRS catalogue includes a broader range of low-concentration groups, which could lead to new insights in the study of galaxy formation and evolution.

The full details of this research can be found in the paper titled "AXES-2MRS: A new all-sky catalogue of extended X-ray galaxy groups" available on arXiv with the identifier arXiv:2403.17061.