Astrophys. J., 617, 240-261 (2004/December-2)
Metallicities of 0.3<z<1.0 galaxies in the GOODS-north field.
KOBULNICKY H.A. and KEWLEY L.J.
Abstract (from CDS):
We measure nebular oxygen abundances for 204 emission-line galaxies with redshifts 0.3<z<1.0 in the Great Observatories Origins Deep Survey-North (GOODS-N) field using spectra from the Team Keck Redshift Survey. We also provide an updated analytic prescription for estimating oxygen abundances using the traditional strong emission line ratio, R23, based on the photoionization models of Kewley & Dopita. We include an analytic formula for very crude metallicity estimates using the [N II]λ6584/Hα ratio. Oxygen abundances for GOODS-N galaxies span the range 8.2≤12+log(O/H)<9.1, corresponding to metallicities between 0.3 and 2.5 times the solar value. This sample of galaxies exhibits a correlation between rest-frame blue luminosity and gas-phase metallicity (i.e., an L-Z relation), consistent with L-Z correlations of previously studied intermediate-redshift samples. The zero point of the L-Z relation evolves with redshift, in the sense that galaxies of a given luminosity become more metal-poor at higher redshift. Galaxies in luminosity bins -18.5<MB←21.5 exhibit a decrease in average oxygen abundance by 0.14±0.05 dex from z=0 to 1. This rate of metal enrichment means that 28%±0.07% of metals in local galaxies have been synthesized since z=1, in reasonable agreement with the predictions based on published star formation rate densities, which show that ∼38% of stars in the universe have formed during the same interval. The slope of the L-Z relation may evolve, in the sense that the least luminous galaxies at each redshift interval become increasingly metal-poor compared to more luminous galaxies. We interpret this change in slope as evidence for more rapid chemical evolution among the least luminous galaxies (MB>-20), consistent with scenarios whereby the formation epoch for less massive galaxies is more recent than for massive galaxies.
Galaxies: Abundances - Galaxies: Evolution - Galaxies: Fundamental Parameters - Galaxies: Starburst - ISM: H II Regions - ISM: Abundances
VizieR on-line data:
<Available at CDS (J/ApJ/617/240): table1.dat>
Table 1, col(1): [KK2004b] NNN (Nos 1-204) = col(2): TKRS NNNNN N=204 among (Nos 448-13683).
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