DETERMINING THE LARGE-SCALE ENVIRONMENTAL DEPENDENCE OF GAS-PHASE METALLICITY IN DWARF GALAXIES

ABSTRACT 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, provi...

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Bibliographic Details
Published in:The Astrophysical journal 2017-01, Vol.834 (2), p.186
Main Authors: Douglass, Kelly A., Vogeley, Michael S.
Format: Article
Language:English
Subjects:
ABUNDANCE
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Blue stars
Chemical evolution
COMPARATIVE EVALUATIONS
DENSITY
Dwarf galaxies
Electron energy
ELECTRON TEMPERATURE
ELECTRONS
ELEMENT ABUNDANCE
Emission lines
ENVIRONMENT
Extreme values
Fluxes
GALACTIC EVOLUTION
GALAXIES
galaxies: abundances
galaxies: dwarf
galaxies: evolution
METALLICITY
Organic chemistry
OXYGEN
OXYGEN IONS
Sky surveys (astronomy)
STAR EVOLUTION
Star formation
STARS
Stars & galaxies
UNIVERSE
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Summary:ABSTRACT 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] λ3727, [O iii] λ4363, and [O iii] λλ4959, 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 reprocessed 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.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/834/2/186