Pruning the Lyman α forest of Q1331 +170

Varsha P. Kulkarni, Keliang Huang, Richard F. Green, Jill Bechtold, Daniel E. Welty, Donald G. York

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


We present a study of the Lyman α forest of the QSO 1331 + 170 in the range 1.67 < Zabs < 2.10 at 18 km s-1 resolution. Our analysis includes a careful search for previously unidentified heavy-element systems, and incorporates detailed deblending of Lyα forest lines from heavy-element lines. Various statistical properties of Lyα forest lines, such as distributions of equivalent widths, H I column densities, Doppler parameters and pair-velocity separations, are computed. The effect on these properties of employing different limiting approaches to heavy-element deblending, and profile-fitting of the lines, is illustrated. Our data suggest that the NH1 distribution may not be fitted adequately by a single power law, i.e., that there may be a relative deficit of strong lines as compared with the predictions of a single power law. However, larger samples are required to verify this deficit. The median b value is ≈ 32 km s-1. No significant correlation is observed between NH1 and b. An excess on the scale of ∼ 100 km s-1 is seen in the pair-velocity correlations, at the level of ∼ 2.6σ for the conservative sample and at the level of ∼ 4.9σ for the less conservative sample. Marginal excess correlation is seen in both the samples at the ≳ 2σ level on scales of ∼ 800-1000 km s-1, and also on scales of ∼ 6000 km s-1.

Original languageEnglish (US)
Pages (from-to)197-218
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 1996


  • Intergalactic medium
  • Quasars: absorption lines
  • Quasars: individual: Q1331 + 170

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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