The gas metallicity gradient and the star formation activity of disc galaxies

TL;DR

This study uses simulated galaxies to explore how gas metallicity gradients relate to stellar mass and star formation, revealing evolutionary trends and the impact of galaxy interactions on metallicity profiles.

Contribution

It provides new insights into the evolution of metallicity gradients in simulated galaxies across redshifts and their connection to galaxy interactions and morphology.

Findings

Low-mass galaxies have steeper metallicity gradients at z ~0.

Gas-phase metallicity slopes align with observations at z ~0.

Galaxy interactions can produce both positive and negative metallicity profiles.

Abstract

We study oxygen abundance profiles of the gaseous disc components in simulated galaxies in a hierarchical universe. We analyse the disc metallicity gradients in relation to the stellar masses and star formation rates of the simulated galaxies. We find a trend for galaxies with low stellar masses to have steeper metallicity gradients than galaxies with high stellar masses at z ~0. We also detect that the gas-phase metallicity slopes and the specific star formation rate (sSFR) of our simulated disc galaxies are consistent with recently reported observations at z ~0. Simulated galaxies with high stellar masses reproduce the observed relationship at all analysed redshifts and have an increasing contribution of discs with positive metallicity slopes with increasing redshift. Simulated galaxies with low stellar masses a have larger fraction of negative metallicity gradients with increasing redshift. Simulated galaxies with positive or very negative metallicity slopes exhibit disturbed morphologies and/or have a close neighbour. We analyse the evolution of the slope of the oxygen profile and sSFR for a gas-rich galaxy-galaxy encounter, finding that this kind of events could generate either positive and negative gas-phase oxygen profiles depending on their state of evolution. Our results support claims that the determination of reliable metallicity gradients as a function of redshift is a key piece of information to understand galaxy formation and set constrains on the subgrid physics.