Choirs HI galaxy groups: The metallicity of dwarf galaxies

Sweet, Sarah M., Drinkwater, Michael J., Meurer, Gerhardt, Bekki, Kenji, Dopita, Michael A., Kilborn, Virginia and Nicholls, David C. (2014) Choirs HI galaxy groups: The metallicity of dwarf galaxies. Astrophysical Journal, 782 35: . doi:10.1088/0004-637X/782/1/35

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Author Sweet, Sarah M.
Drinkwater, Michael J.
Meurer, Gerhardt
Bekki, Kenji
Dopita, Michael A.
Kilborn, Virginia
Nicholls, David C.
Title Choirs HI galaxy groups: The metallicity of dwarf galaxies
Journal name Astrophysical Journal   Check publisher's open access policy
ISSN 0004-637X
Publication date 2014-02-10
Year available 2014
Sub-type Article (original research)
DOI 10.1088/0004-637X/782/1/35
Open Access Status File (Publisher version)
Volume 782
Issue 35
Total pages 11
Place of publication Philadelphia, PA, United States
Publisher Institute of Physics Publishing
Language eng
Abstract We present a recalibration of the luminosity-metallicity relation for gas-rich, star-forming dwarfs to magnitudes as faint as MR -13. We use the Dopita et al. metallicity calibrations to calibrate the relation for all the data in this analysis. In metallicity-luminosity space, we find two subpopulations within a sample of high-confidence Sloan Digital Sky Survey (SDSS) DR8 star-forming galaxies: 52% are metal-rich giants and 48% are metal-medium galaxies. Metal-rich dwarfs classified as tidal dwarf galaxy (TDG) candidates in the literature are typically of metallicity 12 + log(O/H) = 8.70 ± 0.05, while SDSS dwarfs fainter than MR = -16 have a mean metallicity of 12 + log(O/H) = 8.28 ± 0.10, regardless of their luminosity, indicating that there is an approximate floor to the metallicity of low-luminosity galaxies. Our hydrodynamical simulations predict that TDGs should have metallicities elevated above the normal luminosity-metallicity relation. Metallicity can therefore be a useful diagnostic for identifying TDG candidate populations in the absence of tidal tails. At magnitudes brighter than MR -16, our sample of 53 star-forming galaxies in 9 H I gas-rich groups is consistent with the normal relation defined by the SDSS sample. At fainter magnitudes, there is an increase in dispersion of the metallicity of our sample, suggestive of a wide range of H I content and environment. In our sample, we identify three (16% of dwarfs) strong TDG candidates (12 + log(O/H) > 8.6) and four (21%) very metal-poor dwarfs (12 + log(O/H) < 8.0), which are likely gas-rich dwarfs with recently ignited star formation.
Keyword Galaxies abundances
Galaxies dwarf
Galaxies formation
Galaxies groups: general
Galaxies star formation
Techniques spectroscopic
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2015 Collection
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