Details

Autor(en) / Beteiligte

• Salzer, John J
• Williams, Anna L
• Gronwall, Caryl

Titel

A Population of Metal-Poor Galaxies with ~L Luminosities at Intermediate Redshifts

Ist Teil von

• The Astrophysical journal, 2009-04, Vol.695 (1), p.L67-L71

Ort / Verlag

IOP Publishing

Erscheinungsjahr

2009

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• We present new spectroscopy and metallicity estimates for a sample of 15 star-forming galaxies with redshifts in the range 0.29-0.42. These objects were selected in the KPNO International Spectroscopic Survey via their strong emission lines seen in red objective-prism spectra. Originally thought to be intermediate-redshift Seyfert 2 galaxies, our new spectroscopy in the far red has revealed these objects to be metal-poor star-forming galaxies. These galaxies follow a luminosity-metallicity (L - Z) relation that parallels the one defined by low-redshift galaxies, but is offset by a factor of more than 10 to lower abundances. The amount of chemical and/or luminosity evolution required to place these galaxies on the local L-Z relation is extreme, suggesting that these galaxies are in a very special stage of their evolution. They may be late-forming massive systems, which would challenge the current paradigm of galaxy formation. Alternatively, they may represent intense starbursts in dwarf-dwarf mergers or a major infall episode of pristine gas into a pre-existing galaxy. In any case, these objects represent an extreme stage of galaxy evolution taking place at relatively low redshift.