The Gas-Phase Mass-Metallicity Relation of Dwarf Galaxies Across Large-Scale Environments Using the CAVITY Parent Sample

Abstract

The gas-phase mass-metallicity relation (MZR) of galaxies shows a noticeable break in slope and increased scatter at low stellar masses, suggesting that the physical processes governing chemical enrichment differ between dwarf and high-mass systems. Dwarf galaxies are highly susceptible to internal and environmental mechanisms due to shallow potential wells. We assess whether a single MZR describes dwarf galaxies across diverse large-scale environments using the CAVITY parent sample. We examine the MZR and star formation rate (SFR) of dwarfs with stellar masses 8.9 < log(M_star/M_sun) < 9.5. Using SDSS optical spectra, we measured emission line fluxes via the pyPipe3D pipeline to derive the MZR and SFR for 353, 311, and 22 dwarf galaxies in voids, filaments, and clusters, respectively. We find a systematic variation in the MZR slope, which is steeper in voids (0.28 +/- 0.03) and progressively flatter in clusters (0.17 +/- 0.08), indicating an environmental dependence in this mass regime. When separated by local environment, isolated and non-isolated dwarfs in voids show no significant differences. Isolated dwarfs in filaments exhibit properties similar to void counterparts. However, non-isolated filament galaxies display flatter MZR slopes, comparable to cluster dwarfs. We report both large- and local-scale environmental dependencies in the gas-phase metallicity and MZR slope. Consistent with the pre-processing framework, our results indicate that the local environment becomes significant within cosmic web filaments, affecting the chemical enrichment and star formation of low-mass systems. This suggests that part of the MZR scatter in dwarf galaxies arises from environmental effects.