The O/C abundance ratio in absorbing gas clouds at high redshift

Reimers, D.; Vogel, S. N.; Hagen, H. J.; Engels, D.; Groote, D.; Wamsteker, W.; Clavel, J.; Rosa, M. R.

doi:10.1038/360561a0

Cited by 58 publications

(70 citation statements)

References 13 publications

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“…For realistic spectral intensity distributions (except for the very soft UV background caused by decaying neutrinos; Sciama 1990), He I is undetectable in the optically thin clouds of the Lyα forest proper, although it should be present in Lyman limit systems (Miralda-Escudé & Ostriker 1992). Indeed, He I yielded the first detection of helium at high redshift, when absorption by its 504-Å line was found in HST FOS data of several optically thick (z ∼ 2) metal systems towards the bright QSO HS1700+64 (Reimers et al 1992, Reimers & Vogel 1993. The ionization state of He I is less easy to interpret because of the possible presence of internal sources of radiation and unknown shielding effects.…”

Section: The Helium Lyman Alpha Forestmentioning

confidence: 96%

The Lyman Alpha Forest in the Spectra of Quasistellar Objects

Rauch

1998

Annu. Rev. Astron. Astrophys.

459

325

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Observations of redshifted Lyman α (Lyα) forest absorption in the spectra of quasistellar objects (QSOs) provide a highly sensitive probe of the distribution of gaseous matter in the universe. Over the past two decades, optical spectroscopy with large ground-based telescopes, and more recently ultraviolet (UV) spectroscopy from space, have yielded a wealth of information on what appears to be a gaseous, photoionized intergalactic medium (IGM), partly enriched by the products of stellar nucleosynthesis, residing in coherent structures over many hundreds of kiloparsecs.Recent progress with cosmological hydro-simulations based on hierarchical structure formation models has led to important insights into the physical structures giving rise to the forest. If these ideas are correct, a truly inter-and protogalactic medium [at high redshift (z ∼ 3), the main repository of baryons] collapses under the influence of dark matter gravity into flattened or filamentary structures, which are seen in absorption against background QSOs. With decreasing redshift, galaxies forming in the denser regions may contribute an increasing part of the Lyα absorption cross section. Comparisons between large data samples from the new generation of telescopes and artificial Lyα forest spectra from cosmological simulations promise to become a useful cosmological tool.

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Section: The Helium Lyman Alpha Forestmentioning

confidence: 96%

The Lyman Alpha Forest in the Spectra of Quasistellar Objects

Rauch

1998

Annu. Rev. Astron. Astrophys.

459

325

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“…We have also studied a possible contribution by other metal line systems and found no significant contribution among the known 21 metal line systems. Even in case of HS 1700+6416 with its extremely rich metal line spectrum (at least 7 Lyman limit systems, Reimers et al 1992) only 13% of the He  forest features are affected .…”

Section: Analysis Of the H I And He Ii Lyα Forestmentioning

confidence: 99%

“…The two brightest objects in which the He  Lyα forest has been resolved with FUSE, HE 2347-4342 (Kriss et al 2001) and HS 1700+6416 ) have been discovered already with IUE to have "clear" lines of sight (Reimers et al 1989(Reimers et al , 1997. QSO 1157+3143 was discovered to have a transparent line of sight in the course of 2 HST survey programs (GO 7471 and GO 8287) on altogether 32 bright targets from the Hamburg surveys.…”

Section: Observationsmentioning

confidence: 99%

Intergalactic HeII absorption towards QSO 1157+3143

Reimers¹,

Fechner²,

Hagen³

et al. 2005

A&A

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We report the discovery of a further line of sight allowing detection of He  Lyα absorption by the intergalactic medium. A HST/STIS survey of 32 bright z ∼ 3 quasars selected from the Hamburg Quasar Surveys yielded one detection toward QSO 1157+3143 (z ∼ 3, B 17). A 10 orbit follow-up spectrum reveals a UV spectrum significantly suppressed by two intervening Lyman limit systems at z = 2.77 and 2.94, but with the continuum flux recovering sufficiently shortward of ∼1700 Å to allow study of the He  absorption spectrum in the redshift range 2.75 ≤ z ≤ 2.97. The absorption is characterized by alternating voids and dense filament structures seen in both He  and H . Attempts to model the He  opacity in terms of H  Lyα forest absorption are not successful in the voids, suggesting that He  reionization is not complete between z = 2.77 and 2.97 or that an optically thin Lyman limit system with z ≈ 0.3 is responsible for the additional opacity.

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“…Consequently, our aim in this project is to find a number of very bright quasars in the south similar to those found in the north (Q1107+487: m(v) = 16.7 & z em = 3.0; Q1442+295, m(v) = 16.2 & z em = 2.7 (Sanduleak & Pesch, 1989); HS1700+6416, m(v) = 16.1 & z em = 2.72 (Reimers et al 1989); HS1946+7658, m(v) = 15.85 k z em = 3.02 (Hagen et al 1992)). …”

Section: Introductionmentioning

confidence: 99%

The Red Bright Quasar Survey (RBQS)

Sealey¹,

Drinkwater²,

Irwin³

et al. 1995

International Astronomical Union Colloquium

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Abstract. We are using the UK Schmidt telescope (UKST) to carry out a new objective prism survey, covering 2000-3000 square degrees of high galactic latitude sky in the equatorial region. The survey is targeted at discovering both bright (R < 18) quasars in general and bright high redshift (2 < z < 4) quasars in particular, which will be valuable for high resolution spectroscopic follow-up studies. We are using a mixture of ultra-violet excess (XJVX) and a new template matching technique to identify all the bright quasars. Details of the project are discussed and some preliminary results of the survey are presented.

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The O/C abundance ratio in absorbing gas clouds at high redshift

Cited by 58 publications

References 13 publications

The Lyman Alpha Forest in the Spectra of Quasistellar Objects

The Lyman Alpha Forest in the Spectra of Quasistellar Objects

Intergalactic HeII absorption towards QSO 1157+3143

The Red Bright Quasar Survey (RBQS)

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