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

doi:10.1086/185867

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

Steward Observatory

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19 Scopus citations

Abstract

We have obtained new IUE observations of PG 1115+080 (z_em = 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 n_HeI(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 T_IGM-log n_He plane according to the shock-heated and photoionized IGM models. The predominantly shock-heated IGM model requires that T_IGM ≥ 10^5.3 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 N_H of 3 × 10¹⁶ cm^-2 for z_lens ≳ 0.39.

Original language	English (US)
Pages (from-to)	L29-L32
Journal	Astrophysical Journal
Volume	364
Issue number	2 PART 2
DOIs	https://doi.org/10.1086/185867
State	Published - 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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title = "IUE observations of PG 1115 + 080: The He I Gunn-Peterson test and a search for the lensing galaxy",

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.",

keywords = "Galaxies: intergalactic medium, Gravitational lenses, Quasars, Ultraviolet: spectra",

author = "Tripp, {Todd M.} and Green, {Richard F.} and Jill Bechtold",

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doi = "10.1086/185867",

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AU - Green, Richard F.

AU - Bechtold, Jill

PY - 1990/12/1

Y1 - 1990/12/1

N2 - 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.

AB - 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.

KW - Galaxies: intergalactic medium

KW - Gravitational lenses

KW - Quasars

KW - Ultraviolet: spectra

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

Abstract

Keywords

ASJC Scopus subject areas

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