Oral Presentation

Deriving Galaxy Stellar Mass Functions of Local Massive Clusters Based on Dense Spectroscopy

Author(s): Jong-in Park (Seoul National University), Jubee Sohn (Seoul National University)

Presenter: Jong-in Park (Seoul National University)

We present the stellar mass functions (SMFs) of galaxies in the nine most massive clusters at $0.06 < z < 0.11$, based on an exceptionally dense spectroscopic survey. The Massive Cluster Survey using Hectospec (MACH) is a deep and highly complete spectroscopic survey of nearby massive clusters, yielding more than 500 confirmed cluster members within $R_{200}$ for each system. Using these spectroscopically identified members, we construct the cluster SMFs down to $\log~(M_{*} / M_{\odot}) > 9.5$. For comparison, we also derive the field SMF within the same redshift range using SDSS spectroscopy. The MACH cluster SMFs show a significant excess at the high-mass end ($\log (M_{*} / M_{\odot}) > 11.4$) relative to the field, indicating that massive galaxies preferentially form in dense cluster environments. We further divide the populations into quiescent and star-forming galaxies and derive their respective SMFs. At intermediate masses ($9.5 < \log (M_{*} / M_{\odot}) < 10.5$), the number of quiescent galaxies is higher in clusters than in the field, suggesting more effective quenching of galaxies in this mass range within cluster environments. We also compare the MACH cluster SMFs to those from high-redshift clusters and find that their evolution is broadly consistent with predictions from the IllustrisTNG-300 simulation. Our results demonstrate that SMFs based on dense spectroscopic membership provide crucial constraints for understanding galaxy evolution in cluster environments.