Progress in studies of intergalactic He II absorption

Wei Zheng, S. F. Anderson, G. A. Kriss, K. Chiu, D. Haggard, D. P. Schneider, C. J. Hogan, D. G. York, S. Burles, A. Meiksin

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1 Scopus citations


Significant progress has been made in the last decade toward an understanding of the intergalactic He II absorption. At redshifts z < 2.8, individual absorbers are found to be ionised mainly by a hard quasar continuum, but their ionisation states vary considerably and the ionising radiation field may have contributions from a soft stellar continuum. The He II opacity increases significantly at z ∼ 2.8, suggesting a possible end of the general reionisation of intergalactic He II. Using the massive SDSS database and UV selection with HST and GALEX, we have found new quasars at z ≥ 3.5, with detected He II absorption. Future observations will pinpoint the epoch of reionisation of the intergalactic He II.

Original languageEnglish (US)
Pages (from-to)484-486
Number of pages3
JournalProceedings of the International Astronomical Union
Issue numberC199
StatePublished - 2005

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science


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