paper

Echelle Spectroscopy of QSO Absorption Line Systems with Metals in the Direction of HS 1700+6416

arXiv:astro-ph/9703080 · doi:10.1086/313031

Abstract

We present a high signal-to-noise high resolution spectrum of the radio-quiet QSO HS1700+6416 (z = 2.72). Analysis of the absorption line systems with metals yields the following results. (1) The dense cluster of C IV doublets at 2.432 < z(abs) < 2.441 shows the weak line of one C IV absorber apparently aligned with the strong line of a different C IV doublet, i.e., line locked, for two pairs of C IV absorbers. This is surprising since these absorption lines are displaced by more than 24000 km/s from the QSO redshift, but it is possible that these alignments are coincidental. (2) Physical conditions in the Lyman limit absorber at z(abs) = 2.3150 differ significantly from the Galactic gaseous halo, and photoionization models require [Si/H] > -0.95 and [Al/H] > -0.96 for the strongest component of this absorber. Abundances of three other Lyman limit absorbers are also derived from photoionization models. (3) Unsaturated C IV and rather strong N V are detected in the associated absorber at z(abs) = 2.7125. The apparent column density profiles indicate that N V is affected by unresolved saturation or that the N V absorbing gas does not completely cover the QSO flux source. From photoionization models we derive [N/H] > -0.65 and [C/H] > -0.82. (4) We tentatively conclude that the number of Mg II systems detected per unit redshift is dominated by weak Mg II lines with rest equivalent width less than 0.3 A.

58 pages including figures and tables (AASTeX), accepted for publication in ApJS

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