A semi-analytical perspective on massive red galaxies

Abstract

Context. The evolution of galaxies within a self-consistent cosmological context remains one of the most outstanding and challenging topics in modern galaxy formation theory. Investigating the assembly history and various formation scenarios of the most massive and passive galaxies, particularly those found in the densest clusters, will enhance understanding of why galaxies exhibit such a remarkable diversity in structure and morphology. Aims. In this paper, we simultaneously investigate the assembly history and redshift evolution of semi-analytically modelled galaxy properties of luminous and massive central galaxies between 0.56 < z < 4.15 alongside their connection to their halos as a function of large-scale environment. Methods. We extracted sub-samples of galaxies from a mock catalogue representative of the well-known BOSS-CMASS sample, which includes the most massive and passively evolving system known today. Utilising typical galaxy properties such as star formation rate, (ɡ-i) colour, and cold gas-phase metallicity (Zcold), we tracked the redshift evolution of these properties across the main progenitor trees. Results. We present results on galaxy and halo properties, including their growth and clustering functions, for each of our sub-samples. Our findings indicate that galaxies in the highest stellar and halo mass regimes are the least metal enriched (using Zcold as a proxy) and consistently exhibit significantly larger black hole masses and higher clustering amplitudes compared to sub-samples selected by such properties as colour or star formation rate. This population forms later and retains large reservoirs of cold gas. In contrast, galaxies in the intermediate and lower stellar or halo mass regimes consume their cold gas at a higher redshift and were among the earliest and quickest to assemble their stellar and black hole masses. In addition, we observed a clear trend where the clustering of the galaxies selected according to their Zcold-values (either low-Zcold or high-Zcold) depends on the density of their location within the large-scale environment. Conclusions. We assume that the galaxies in the low-Zcold and high-Zcold sub-samples form and evolve through distinct evolutionary channels that are predetermined by their location within the large-scale environment of the cosmic web. Furthermore, their clustering dependence on the environment could be an important area for further investigation.