Clues to the Origin of the Mass-Metallicity Relation: Dependence on Star Formation Rate and Galaxy Size

TL;DR

This study analyzes how galaxy size and star formation rate influence the mass-metallicity relation, revealing that larger or more actively star-forming galaxies tend to have lower metallicities, with implications for galaxy evolution models.

Contribution

It demonstrates the dependence of the mass-metallicity relation on galaxy size and star formation rate, providing insights into the physical processes affecting galaxy chemical evolution.

Findings

Galaxies with high SSFR or large r_h have lower metallicities by up to 0.2 dex.

Dependence on SSFR and size suggests roles for galactic winds, abundance gradients, and environment.

Results help refine models of galaxy formation and chemical enrichment.

Abstract

We use a sample of 43,690 galaxies selected from the Sloan Digital Sky Survey Data Release 4 to study the systematic effects of specific star formation rate (SSFR) and galaxy size (as measured by the half light radius, r_h) on the mass-metallicity relation. We find that galaxies with high SSFR or large r_h for their stellar mass have systematically lower gas phase-metallicities (by up to 0.2 dex) than galaxies with low SSFR or small r_h. We discuss possible origins for these dependencies, including galactic winds/outflows, abundance gradients, environment and star formation rate efficiencies.