The growth of disks and bulges during hierarchical galaxy formation. II: metallicity, stellar populations and dynamical evolution

TL;DR

This study uses a new semi-analytic galaxy formation model to analyze how stellar populations, metallicity, and dynamical evolution relate to galaxy formation history and angular momentum, aligning with observed galaxy classifications.

Contribution

Introduces a semi-analytic model incorporating angular momentum evolution and new star formation recipes, improving predictions of galaxy metallicity and structural properties.

Findings

Model reproduces the stellar mass-metallicity relation for massive galaxies.

Different galaxy evolutionary channels correspond to distinct mass-size relations.

Stellar population properties correlate with angular momentum loss during assembly.

Abstract

We investigate the properties of the stellar populations of model galaxies as a function of galaxy evolutionary history and angular momentum content. We use the new semi-analytic model presented in Tonini et al. (2016). This new model follows the angular momentum evolution of gas and stars, providing the base for a new star formation recipe, and treatment of the effects of mergers that depends on the central galaxy dynamical structure. We find that the new recipes have the effect of boosting the efficiency of the baryonic cycle in producing and recycling metals, as well as preventing minor mergers from diluting the metallicity of bulges and ellipticals. The model reproduces the stellar mass - stellar metallicity relation for galaxies above 1e10 solar masses, including Brightest Cluster Galaxies. Model disks, galaxies dominated by instability-driven components, and merger-driven objects each stem from different evolutionary channels. These model galaxies therefore occupy different loci in the galaxy mass-size relation, which we find to be in accord with the Atlas 3D classification of disk galaxies, fast rotators and slow rotators. We find that the stellar populations' properties depend on the galaxy evolutionary type, with more evolved stellar populations being part of systems that have lost or dissipated more angular momentum during their assembly history.