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Astron. Astrophys. 354, 17-27 (2000)


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Elemental abundances of high redshift quasars  *

M. Dietrich 1,2 and U. Wilhelm-Erkens 1

1 Landessternwarte Heidelberg, Königstuhl, 69117 Heidelberg, Germany
2 Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055, USA

Received 12 August 1999 / Accepted 13 December 1999

Abstract

A sample of 16 high redshift quasars with 2.4 [FORMULA]z[FORMULA]3.8 was observed with moderate spectral resolution in the restframe ultraviolet. The emission-line fluxes of NV 1240, CIV1549, and HeII1640 were used to estimate the metallicity of the line emitting gas. The line ratios were investigated within the frame work of models presented by Hamann & Ferland (1992, 1993, 1999). The scaled solar abundance model yields inconsistent results for the metallicity while the rapid star formation scenario is successful in indicating a common range of overabundance on base of NV1240/CIV1549 and NV1240/HeII1640 line ratios. We estimated an abundance of Z [FORMULA] 8 [FORMULA] of the line emitting gas given by NV/CIV and NV/HeII. Assuming an evolution time scale of [FORMULA]1 Gyr and a cosmological model with [FORMULA]0.3, [FORMULA]0.7, and Ho [FORMULA] 65 km s-1 Mpc-1 the first violent star formation epoch should start at a redshift of zf [FORMULA] 6 to 10.

Key words: galaxies: quasars: emission lines – galaxies: quasars: general – cosmology: early Universe

* Based on observations collected at the German-Spanish Astronomical Centre, Calar Alto, operated by the Max-Planck-Institut für Astronomie (MPIA), Heidelberg, jointly with the Spanish National Commission for Astronomy; McDonald Observatory/Texas, University of Austin/TX, USA; the VLT-UT1 operated on Cerro Paranal (Chile) by the European Southern Observatory, Present address: Department of Astronomy, University of Florida

Send offprint requests to: M. Dietrich

Correspondence to: e-mail:dietrich@astro.ufl.edu

© European Southern Observatory (ESO) 2000

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