Determining the large-scale environmental dependence of gas-phase
  metallicity in dwarf galaxies
  We study how the cosmic environment affects galaxy evolution in the Universe
by comparing the metallicities of dwarf galaxies in voids with dwarf galaxies
in more dense regions. Ratios of the fluxes of emission lines, particularly
those of the forbidden [O III] and [S II] transitions, provide estimates of a
region's electron temperature and number density. From these two quantities and
the emission line fluxes [O II] 3727, [O III] 4363, and [O III] 4959,5007, we
estimate the abundance of oxygen with the Direct Te method. We estimate the
metallicity of 42 blue, star-forming void dwarf galaxies and 89 blue,
star-forming dwarf galaxies in more dense regions using spectroscopic
observations from the Sloan Digital Sky Survey Data Release 7, as re-processed
in the MPA-JHU value-added catalog. We find very little difference between the
two sets of galaxies, indicating little influence from the large-scale
environment on their chemical evolution. Of particular interest are a number of
extremely metal-poor dwarf galaxies that are less prevalent in voids than in
the denser regions.
