Seminaire Lagrange -- Ilaria Marini (ESO) -- The X-ray emission of galaxy groups: detectability and selection effects

The X-ray emission of galaxy groups: detectability and selection effects

The distribution of baryonic matter within group-scale halos is shaped by complex astrophysical processes, including feedback from active galactic nuclei (AGN) and star formation, leading to deviations from theoretical self-similar predictions. Several studies indicate that thermal feedback significantly influences the intragroup medium, affecting its thermodynamic state and overall baryonic content. To assess these effects and control for systematics, we conduct a simultaneous analysis of both observations (eROSITA, SDSS, GAMA) and cosmological hydrodynamical simulations. We construct a multiwavelength lightcone that replicates real observational conditions, generating synthetic datasets that closely mimic observed galaxy groups in X-ray and optical wavelengths. This approach enables us to disentangle the impact of selection effects, revealing that X-ray detectability is primarily driven by AGN feedback at early times and by assembly history at later stages. By combining simulated and observed X-ray and optical properties, we gain insight into the role of these processes in shaping the hot gas content of galaxy groups. These results provide a crucial framework for future studies on the evolution and baryonic composition of galaxy groups.