Hst/stis observations of the heii gunn-peterson effect towards he 2347-4342
Dec, 200043 pages
Published in:
- ASP Conf.Ser. 240 (2001) 17
Contribution to:
- Published: 2001
e-Print:
- astro-ph/0012193 [astro-ph]
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Abstract: (Astronomical Society of the Pacific)
We present HST/STIS observations of the He II Gunn-Peterson effect at z~3 towards Q 0302-003 and HE 2347-4342. The observed opacities are significantly larger than the ones predicted by any existing model aimed at reproducing the characteristics of the intergalactic medium. The ratio of He II to HI column densities required to reproduce these opacities indicates that the UV background radiation is softer than the usually assumed Haardt & Madau spectrum, which may be explained by a significant stellar contribution at the HI Lyman limit.References(45)
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