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Title:
Progress in studies of intergalactic He II absorption
Authors:
Zheng, Wei; Anderson, S. F.; Kriss, G. A.; Chiu, K.; Haggard, D.; Schneider, D. P.; Hogan, C. J.; York, D. G.; Burles, S.; Meiksin, A.
Publication:
Probing Galaxies through Quasar Absorption Lines, IAU Colloquium Proceedings of the International Astronomical Union 199, held March 14-18 2005, Shanghai, People's Republic of China, edited by Peter R. Williams, Cheng-Gang Shu and Brice Menard. Cambridge: Cambridge University Press 2005., pp.484-486
Publication Date:
03/2005
Origin:
CUP
DOI:
10.1017/S1743921305003169
Bibliographic Code:
2005pgqa.conf..484Z

Abstract

Significant progress has been made in the last decade toward an understanding of the intergalactic He II absorption. At redshifts z, 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.
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