Speaker
Description
Massive central galaxies ($M_\star>10^{11.2}M_\odot$) in clusters and their satellites offer insights into the assembly history of their host massive dark matter halos that are crucial for cosmology. Therefore, it is necessary to establish a clear picture of their galaxy-halo connection. Recent works using deep image and weak lensing suggest that the stellar mass in the outskirt of massive central galaxies at low-redshift is a good halo mass proxy. Besides, massive halos with similar mass but different concentration show different distribution on the central galaxy stellar mass - richness plane. These intriguing results need more investigation due to they have important implications for the cluster cosmology and the study of assembly bias of massive halos. In this study, we check whether the hydro-simulations can reproduce the results and provide some insights. With the massive galaxies from Illustris and IllustrisTNG simulation, we confirm that the outskirt mass of massive central galaxies is a promising halo mass proxy in three simulations with different resolution and physical recipes for galaxy formation, outperforming the total accreted stellar mass (ex-situ). Additionally, we explore the TNG300 massive galaxies distribution on the outskirt mass - richness plane. We identify massive halos missed by the richness-based selection and uncover a systematic halo concentration trend over this parameter space. These results could help us to understand the assembly bias of massive halos in the era of DESI and better utilize the cosmological potential in massive halos.
