IUE observations of PG 1115 + 080: The He I Gunn-Peterson test and a search for the lensing galaxy

Todd M. Tripp, Richard F. Green, Jill Bechtold

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

We have obtained new IUE observations of PG 1115+080 (zem = 1.722), the "triple quasar," in order to carry out the He I Gunn-Peterson test with greater sensitivity and to search for a Lyman-limit discontinuity which could reveal the redshift of the gravitational lens. We find that nHeI(z = 1.722) ≤ 7 × 10-11h100 cm-3 at the 3 σ level. We have used this density to set a curve of constraint in the log TIGM-log nHe plane according to the shock-heated and photoionized IGM models. The predominantly shock-heated IGM model requires that TIGM ≥ 105.3 K. If the IGM is both photoionized by the standard QSO diffuse radiation field and shock-heated, then the limits on hydrogen Lyman-alpha provide more stringent limits on the density and temperature of the IGM. We have found no evidence of the gravitational lens, placing an upper limit on NH of 3 × 1016 cm-2 for zlens ≳ 0.39.

Original languageEnglish (US)
Pages (from-to)L29-L32
JournalAstrophysical Journal
Volume364
Issue number2 PART 2
DOIs
StatePublished - Dec 1 1990

Keywords

  • Galaxies: intergalactic medium
  • Gravitational lenses
  • Quasars
  • Ultraviolet: spectra

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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