paper

The DEEP2 Galaxy Redshift Survey: Discovery of Luminous, Metal-poor, Sta r-forming Galaxies at Redshifts z~0.7

arXiv:astro-ph/0510843 · doi:10.1086/499232

Abstract

We have discovered a sample of 17 metal-poor, yet luminous, star-forming galaxies at redshifts z~0.7. They were selected from the initial phase of the DEEP2 survey of 3900 galaxies and the Team Keck Redshift Survey (TKRS) of 1536 galaxies as those showing the temperature-sensitive [OIII]l4363 auroral line. These rare galaxies have blue luminosities close to L*, high star formation rates of 5 to 12 solar masses per year, and oxygen abundances of 1/3 to 1/10 solar. They thus lie significantly off the luminosity-metallicity relation found previously for field galaxies with strong emission lines at redshifts z~0.7. The prior surveys relied on indirect, empirical calibrations of the R23 diagnostic and the assumption that luminous galaxies are not metal-poor. Our discovery suggests that this assumption is sometimes invalid. As a class, these newly-discovered galaxies are: (1) more metal-poor than common classes of bright emission-line galaxies at z~0.7 or at the present epoch; (2) comparable in metallicity to z~3 Lyman Break Galaxies but less luminous; and (3) comparable in metallicity to local metal-poor eXtreme Blue Compact Galaxies (XBCGs), but more luminous. Together, the three samples suggest that the most-luminous, metal-poor, compact galaxies become fainter over time.

arXiv commentThis is a .tgz file. It should create the following files: texto.tex, tab1.tex, f1.eps and f2.eps. The LaTeX style used is emulateapj.cls, version November 26, 2004. This submission is 5 pages long, one table and two figures. To appear in ApJL

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