A high-resolution study of the absorption spectra of the QSOs Q0002-422 and Q0453-423

Abstract

High-resolution spectroscopic observations in the wavelength range from 3800 to 5400 A are presented for two bright southern QSOs, Q0002-422 (emission redshift of 2.763) and Q0453-423 (emission redshift of 2.656). Data on the emission and absorption systems are computed, and five absorption-line systems of differing probability are identified in each QSO. These data are then combined with previous data on PKS 2126-158 (emission redshift of 3.280) in order to analyze the properties of the identified absorption systems in high-redshift QSOs. The results show that: (1) the absorption systems are similar in type, line strength, velocity dispersion, and redshift distribution among the three QSOs; (2) a radius of 30 kpc of absorbing material is required if these systems arise in galactic halos; (3) the systems at high redshift are probably in photoionization equilibrium; (4) the clouds responsible for the absorption cannot supply a cosmologically interesting mass density; and (5) the evidence supports the 'intervening galaxy' hypothesis for the origin of QSO absorption lines.