# Influence of the Void Environment on Chemical Abundances in Dwarf Galaxies and Implications for Connecting Star Formation and Halo Mass

## TL;DR

This study investigates how the void environment influences the chemical evolution of dwarf galaxies, revealing subtle differences in elemental abundances and star formation processes compared to denser regions.

## Contribution

It introduces a new method for estimating oxygen abundance across all redshifts and compares chemical properties of dwarf galaxies in different environments, highlighting environmental effects.

## Key findings

- Void dwarf galaxies have similar oxygen abundances to those in denser regions.
- Void dwarf galaxies show slightly higher neon and lower nitrogen abundances.
- Secondary nitrogen production begins at lower stellar masses in void dwarf galaxies.

## Abstract

We study how the void environment affects galactic chemical evolution by comparing the oxygen and nitrogen abundances of dwarf galaxies in voids with dwarf galaxies in denser regions. Using spectroscopic observations from SDSS DR7, we estimate oxygen, nitrogen, and neon abundances of 889 void dwarf galaxies and 672 dwarf galaxies in denser regions. A substitute for the [OII] 3727 doublet is developed, permitting oxygen abundance estimates of SDSS dwarf galaxies at all redshifts with the Direct Te method. We find that void dwarf galaxies have about the same oxygen abundance and Ne/O ratio, slightly higher neon abundances, and slightly lower nitrogen abundance and N/O ratio than dwarf galaxies in denser environments. We conclude that the void environment has a slight influence on dwarf galaxy chemical evolution. Our mass-N/O relationship shows that the secondary production of nitrogen commences at a lower stellar mass in void dwarf galaxies than in dwarf galaxies in denser environments. Our dwarf galaxy sample demonstrates a strong anti-correlation between the sSFR and N/O ratio, providing evidence that oxygen is produced in higher mass stars than those which synthesize nitrogen. The lower N/O ratios and smaller stellar mass for secondary nitrogen production seen in void dwarf galaxies may indicate both delayed star formation and a dependence of cosmic downsizing on the large-scale environment. A shift toward slightly higher oxygen abundances in void dwarf galaxies could be evidence of larger ratios of dark matter halo mass to stellar mass in voids than in denser regions.