A semi-analytical perspective on massive red galaxies: I. Assembly history, environment & redshift evolution

TL;DR

This study uses semi-analytical models to explore the assembly history, environmental dependence, and redshift evolution of massive, passive galaxies, revealing how their properties and clustering relate to their large-scale environment and formation pathways.

Contribution

It provides a detailed analysis of the assembly and evolution of massive galaxies across redshifts, highlighting environmental influences and differences in galaxy properties based on cold gas metallicity.

Findings

Massive galaxies are less metal-enriched and have larger black holes and clustering amplitudes.

Galaxies in high-mass regimes assemble later and retain cold gas reservoirs.

Clustering depends on cold gas metallicity and environment, indicating distinct evolutionary channels.

Abstract

Investigating the assembly history of the most massive and passive galaxies will enhance our understanding of why galaxies exhibit such a remarkable diversity in structure and morphology. In this paper, we simultaneously investigate the assembly history and redshift evolution of semi-analytically modelled galaxy properties of central galaxies between 0.56 < z < 4.15, alongside their connection to their halos as a function of large-scale environment. We extract sub-samples of galaxies from a mock catalogue representative for the BOSS-CMASS sample, which includes the most massive and passively evolving system known today. Utilising typical galaxy properties such as star formation rate, (g-i) colour, or cold gas-phase metallicity (Zcold), we track the redshift evolution of these properties across the main progenitor trees. We present results on galaxy and halo properties, including their growth and clustering functions. Our findings indicate that galaxies in the highest stellar and halo mass regimes are 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 e.g. colour or star formation rate. This population forms later and also retains large reservoirs of cold gas. In contrast, galaxies in the intermediate and lower stellar/halo mass regimes consume their cold gas at higher redshift and were among the earliest and quickest to assemble. We observe 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. We assume that in particular galaxies in the low/high-Zcold sub-samples form and evolve through distinct evolutionary channels, which are predetermined by their location within the large-scale environment of the cosmic web.