The interplay of internal and external processes in the buildup of disk galaxies: thick-disk star formation histories in AURIGA simulations

TL;DR

This study uses AURIGA simulations to analyze the complex star formation and chemical evolution histories of thick and thin galactic disks, highlighting the roles of internal processes and external accretion.

Contribution

It provides detailed stellar-population analysis of simulated galaxies, revealing the interplay of internal and external factors in disk galaxy evolution.

Findings

Thick disks contain in-situ and ex-situ stellar populations.

Both disks show signs of chemical enrichment and accretion.

Thick disks have complex stellar populations with multiple origins.

Abstract

Recent integral-field spectroscopy observations have revealed that thick- and thin-disk star-formation histories are regulated by the interplay of internal and external processes. We analyze stellar-population properties of 24 spiral galaxies from the AURIGA zoom-in cosmological simulations, to offer a more in-depth interpretation of observable properties. We present edge-on maps of stellar age, metallicity and [Mg/Fe] abundance, and we extract the star-formation and chemical-evolution histories of thin and thick disks. Both show signs of the interplay between internal chemical enrichment and gas and star accretion. Thick disks show particularly complex stellar populations, including an in-situ component, formed from both slowly enriched and accreted more pristine gas, and an additional significant fraction of ex-situ stars.