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
1538-4357
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
Collection year 2015
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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