The Redshift Evolution of the Relation between Stellar Mass, Star Formation Rate, and Gas Metallicity of Galaxies

TL;DR

This study analyzes how the relationship between stellar mass, star formation rate, and metallicity in galaxies evolves over redshift, finding significant evolution that cannot be solely explained by observational biases.

Contribution

It provides evidence for the evolution of the fundamental metallicity relation across redshifts using SDSS data, highlighting the challenge of disentangling intrinsic relations from redshift effects.

Findings

Significant evolution of the relation with redshift (>99%)

Observational effects cannot fully explain the evolution

Degeneracy exists between galaxy properties and redshift

Abstract

We investigate the relation between stellar mass ($M_\star$), star formation rate (SFR), and metallicity ($Z$) of galaxies, so called the fundamental metallicity relation, in the galaxy sample of the Sloan Digital Sky Survey Data Release 7. We separate the galaxies into narrow redshift bins and compare the relation at different redshifts, and find statistically significant ($> 99$%) evolution. We test various observational effects that might cause seeming $Z$ evolution, and find it difficult to explain the evolution of the relation only by the observational effects. In the current sample of low redshift galaxies, galaxies with different $M_\star$ and SFR are sampled from different redshifts, and there is degeneracy between $M_\star$/SFR and redshift. Hence it is not straightforward to distinguish a relation between $Z$ and SFR from a relation between $Z$ and redshift. The separation of the intrinsic relation from the redshift evolution effect is a crucial issue to understand evolution of galaxies.