A sample of lobe-dominated quasars with Mg II absorption lines

Thomas L. Aldcroft, Martin Elvis, Jill Bechtold

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13 Scopus citations


We present a sample of quasars which are lobe-dominated in their radio emission and contain Mg II absorption line systems. This sample will be useful in a search for redshifted H I 21 cm absorbers which are along lines of sight different from the optical. These systems will allow the measurement of the linear size and related physical parameters of the absorption line clouds. Since quasars appropriate for this study are rare, building this sample requires a substantial database of radio and optical observations. We have defined a set of criteria for selecting these objects and obtained the necessary data, from the literature and from new optical and Very Large Array (VLA) observations, to assemble a sample based on these criteria. Out of 4234 Quasi Stellar Objects (QSOs), we find 31 lobe-dominated quasars which are appropriate for optical and radio absorption line study in the Northern hemisphere. We have obtained or located optical spectra for 29 of these 31 quasars. In the optical spectra we find 17 Mg II absorption systems, with redshifts between 0.3 and 1.4 and Mg II λ2796 rest equivalent widths between 0.3 and 2.0 Å. Based on statistics of 21 cm absorption in Mg II selected QSOs we expect this sample of 17 systems to yield one or two new H I absorbers. In this paper we give an analysis of our criteria, discuss the sample, and present new VLA observations of 16 quasars.

Original languageEnglish (US)
Pages (from-to)2054-2063
Number of pages10
JournalAstronomical Journal
Issue number6
StatePublished - Jun 1993

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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