The [OII]/Halpha ratio of emission line galaxies in the 2dF redshift survey

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dc.creatorMouhcine, M.
dc.creatorLewis, I.
dc.creatorJones, B.
dc.creatorLamareille, F.
dc.creatorMaddox, S. J.
dc.creatorContini, T.
dc.date2005-11-29
dc.date.accessioned2026-07-07T12:24:38Z
dc.date.available2026-07-07T12:24:38Z
dc.descriptionWe investigate the systematic variation of the [OII]3727/Halpha flux line ratio as a function of various galaxy properties, i.e., luminosity, metallicity, reddening, and excitation state, for a sample of 1124 emission-line galaxies, with a mean redshift z ~ 0.06, drawn from the Two Degree Field Galaxy Redshift Survey. The mean observed and extinction-corrected emission-line flux ratios agree well with the values derived from the $B$-band selected Nearby Field Galaxy Survey galaxy sample, but are significantly different from the values obtained from the Halpha-selected Universidad Complutense de Madrid Survey galaxy sample. This is because the different selection criteria applied in these surveys lead to a significant difference in the mean extinction and metallicity of different samples. We use the R_{23} parameter to estimate the gas-phase oxygen abundance and find that the extinction-corrected [OII]3727/Halpha ratio depends on the oxygen abundance. For 12+log(O/H)>8.4, we confirm that the emission-line ratio decreases with increasing metallicity. We have extended the relationship further to the metal-poor regime, 12+log(O/H)< 8.4, and find that the correlation between the extinction-corrected [OII]3727/Halpha ratio and the metallicity reverses in comparison to the relationship for metal-rich galaxies. For metal-poor galaxies, in contrast with metal-rich ones, the variation of extinction-corrected [OII]3727/Halpha ratio is correlated with the ionization states of the interstellar gas.
dc.description2005, MNRAS 362, 1143 (16 pages, 16 figures)
dc.identifierhttps://arxiv.org/abs/astro-ph/0511809
dc.identifierhttp://arxiv.org/abs/astro-ph/0511809
dc.identifierMon.Not.Roy.Astron.Soc.362:1143-1156,2005
dc.identifierdoi:10.1111/j.1365-2966.2005.09211.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/214391
dc.subjectAstrophysics
dc.titleThe [OII]/Halpha ratio of emission line galaxies in the 2dF redshift survey
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