Expanding on the Fundamental Metallicity Relation in Dwarf Galaxies with MUSE

TL;DR

This study investigates the fundamental metallicity relation in dwarf galaxies using high-resolution MUSE data, revealing different behaviors of metallicity and star formation across regions and linking gas accretion mechanisms to galaxy mass.

Contribution

It extends the analysis of the FMR to lower-mass, spatially-resolved dwarf galaxies, providing new insights into the role of gas accretion in galaxy evolution.

Findings

SFR surface density anti-correlates with metallicity in low-mass galaxies.

A correlation exists between SFR surface density and stellar mass surface density.

Different behaviors of the MZR and FMR are observed within galaxy regions.

Abstract

The mass-metallicity relation (MZR) represents one of the most important scaling relations in the context of galaxy evolution, comprising a positive correlation between stellar mass and metallicity (Z). The fundamental metallicity relation (FMR) introduces a new parameter, the star formation rate (SFR), in the dependence. While several studies found that Z is anti-correlated with the SFR at fixed mass, the validity of this statement has been questioned extensively and no widely-accepted consensus has been reached yet. With this work, we investigate the FMR in nine nearby, spatially-resolved, dwarf galaxies, using gas diagnostics on integral-field spectroscopic data of the Multi Unit Spectroscopic Explorer (MUSE), pushing such investigations to lower galaxy masses and higher resolutions. We find that both the MZR and FMR exhibit different behaviours within different star forming regions of the galaxies. We find that the SFR surface density - metallicity anti-correlation is tighter in the low-mass galaxies of our sample. For all the galaxies considered, we find a SFR surface density - stellar mass surface density correlation. We propose that the main reason behind these findings is connected to the accretion mechanisms of the gas fuelling star formation -- low-mass, metal-poor galaxies accrete pristine gas from the intergalactic medium, while in more massive and metal-enriched systems the gas responsible for star formation is recycled from previous star forming episodes.