Lucas Kimmig
Galaxy Cluster Abell 2744The galaxy cluster Abell 2744, one of the clusters observed with the Hubble Frontier Fields Program, is one of the most massive clusters in the Universe. Its dynamical state is classified as very active, and from lensing observations it is known that it contains at least eight extremely massive substructures. This configuration as such has been debated to contradict LCDM for several years now, as it has proven difficult for simulations to reproduce this particular cluster successfully. Using one of the largest fully hydrodynamical cosmological simulation volumes from the Magneticum Pathfinder simulation suite, I identified a simulated counterpart of Abell 2744, with not only the substructure masses matching observations but also other properties like shock fronts detected in the X-ray emissions, and show that Abell 2744 is indeed a product of not only one recent major merging event, but rather at least six mergers of structures with mass ratios between 1:2 and 1:20. Furthermore, I showed that the problems in identifying such clusters in LCDM simulations does not actually stem from the lack of these structures with multiple massive substructures, but rather are caused by the very different methods employed to find substructures in simulations and observations, and projections effects. For more details on this study, see Kimmig et al., 2023. |