The Role of Environment in the Mass-Metallicity Relation

TL;DR

This study reveals a significant correlation between galaxy metallicity and environment, showing that more metal-rich galaxies tend to reside in denser regions, and environment contributes notably to the scatter in the mass-metallicity relation.

Contribution

It demonstrates the impact of local environment on galaxy metallicity and quantifies its role in the scatter of the mass-metallicity relation using SDSS data.

Findings

Metal-rich galaxies are found in higher density regions.

A residual metallicity-environment trend exists after accounting for color and luminosity.

Over 15% of the scatter in the mass-metallicity relation is linked to environment.

Abstract

Using a sample of 57,377 star-forming galaxies drawn from the Sloan Digital Sky Survey, we study the relationship between gas-phase oxygen abundance and environment in the local Universe. We find that there is a strong relationship between metallicity and environment such that more metal-rich galaxies favor regions of higher overdensity. Furthermore, this metallicity-density relation is comparable in strength to the color-density relation along the blue cloud. After removing the mean dependence of environment on color and luminosity, we find a significant residual trend between metallicity and environment that is largely driven by galaxies in high-density regions, such as groups and clusters. We discuss the potential source of this relationship between metallicity and local galaxy density in the context of feedback models, with special attention paid to quantifying the impact of environment on the scatter in the mass-metallicity relation. We find that environment is a non-negligible source of scatter in this fundamental relation, with > 15% of the measured scatter correlated with environment.