Correlations between mass, stellar kinematics and gas metallicity in EAGLE galaxies

TL;DR

This study uses EAGLE simulations to explore how galaxy morphology and stellar kinematics influence gas metallicity, revealing complex dependencies that vary with stellar mass and redshift.

Contribution

It uncovers the relationship between stellar kinematics and metallicity, highlighting the roles of feedback, star formation history, and galaxy morphology in this correlation.

Findings

Lower metallicity in rotationally supported galaxies below 10^10 M_sun.

Higher mass galaxies show lower metallicity in prolate shapes.

Redshift evolution affects the strength of the kinematic-metallicity relation.

Abstract

The metallicity of star-forming gas in galaxies from the EAGLE simulations increases with stellar mass. Here we investigate whether the scatter around this relation correlates with morphology and/or stellar kinematics. At redshift $z=0$, galaxies with more rotational support have lower metallicities on average when the stellar mass is below $M_\star\approx 10^{10}~{\rm M}_\odot$. This trend inverts at higher values of $M_\star$, when prolate galaxies show typically lower metallicity. At increasing redshifts, the trend between rotational support and metallicity becomes weaker at low stellar mass but more pronounced at high stellar mass. We argue that the secondary dependence of metallicity on stellar kinematics is another manifestation of the observed anti-correlation between metallicity and star formation rate at a given stellar mass. At low masses, such trends seem to be driven by the different star-formation histories of galaxies and stellar feedback. At high masses, feedback from active galactic nuclei and galaxy mergers play a dominant role.