AXES-2MRS extended X-ray galaxy groups catalog

We analysed temperature and density to the lowest overdensity accessible by the data, obtaining hydrostatic mass estimates at a uniform overdensity of 10000 times the critical, and comparing them to the velocity dispersions of the groups. We explored the relationship between X-ray and optical properties of AXES-2MRS groups through the sigma_v_-L_X_, sigma_v-kT, kT-L_X_, {sigma}_v-M_, and c_200_-L_X_ scaling relations. We find a large spread in the central mass M_10000_, measured by XMM-Newton, to virial mass M_200_, inferred by the velocity dispersion, ratios for galaxy groups.

This can either indicate that large non-thermal pressure of galaxy groups affects our X-ray mass measurements or the effect of a diversity of halo concentrations on the X-ray properties of galaxy groups. Previous catalogues based on detecting the peak of the X-ray emission preferentially sample the high-concentration groups. In contrast, our new catalogue uncovered many low-concentration groups, completely revising our understanding of X-ray groups.