The Mass Assembly History of Galaxies and Clusters of Galaxies

Abstract

We discuss the mass assembly history both on cluster and galaxy scales and their impact on galaxy evolution. On cluster scale, we introduce our on-going PISCES project on Subaru, which plans to target ~15 clusters at 0.4<z<1.3 using the unique wide-field (30') optical camera Suprime-Cam and the spectrograph both in optical (FOCAS, 6') and near-infrared (FMOS, 30'). The main objectives of this project are twofold: (1) Mapping out the large scale structures in and around the clusters on 10-14 Mpc scale to study the hierarchical growth of clusters through assembly of surrounding groups. (2) Investigating the environmental variation of galaxy properties along the structures to study the origin of the morphology-density and star formation-density relations. Some initial results are presented. On galactic scale, we first present the stellar mass growth of cluster galaxies out to z~1.5 based on the near-infrared imaging of distant clusters and show that the mass assembly process of galaxies is largely completed by z~1.5 and is faster than the current semi-analytic models' predictions. We then focus on the faint end of the luminosity function at z~1 based on the Subaru/XMM-Newton Deep Survey imaging data. We show the deficit of red galaxies below M*+2 or 10^{10} Msun, which suggest less massive galaxies are either genuinely young or still vigorously forming stars in sharp contrast to the massive galaxies where mass is assembled and star formation is terminated long time ago.Comment: To appear in the proceedings of IAU colloq. No. 195, "Outskirts of Galaxy Clusters: intense life in the suburbs", Torino, 12-16 March 2004, 7 pages, 7 figures, uses IAU macr