The main systematics in cluster cosmology is the uncertainty in the mass-observable relation. In this paper, we focus on the most direct cluster observable in optical surveys, i.e. richness, and constrain the intrinsic mass-richness (MR) relation of clusters in THE THREE HUNDRED hydrodynamic simulations with two runs: GIZMO-SIMBA and GADGET-X. We find that modeling the richness at fixed halo mass with a skewed Gaussian distribution yields a simpler and smaller scatter compared to the commonly used log-normal distribution. Additionally, we observe that baryon models have a significant impact on the scatter, while exhibiting no influence on the mass dependence and a slight effect on the amplitude in the MR relation. We select member galaxies based on both stellar mass M⋆ and absolute magnitude M. We demonstrate that the MR relation obtained from these two selections can be converted to each other by using the M⋆−M relation. Finally, we provide a 7-parameter fitting result comprehensively capturing the dependence of the MR relation on both stellar mass cutoff and redshift.
@article{arxiv.2404.00321,
title = {Intrinsic mass-richness relation of clusters from THE THREE HUNDRED hydrodynamic simulations},
author = {Mingjing Chen and Weiguang Cui and Wenjuan Fang and Zhonglue Wen},
journal= {arXiv preprint arXiv:2404.00321},
year = {2024}
}