Molecular Hydrogen in high redshift Damped Lyman-α systems

Author: Petitjean, Patrick

Source: Astrophysics and Space Science, Volume 281, Numbers 1-2, July 2002 , pp. 467-470(4)

Publisher: Springer

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I describe briefly the status of an ongoing mini-survey for molecular hydrogen in high-redshift Damped Lyman-α systems using UVES at the VLT. H2 is detected in about 30% of the cases. When H2 is not detected the molecular fraction f = 2N(H2)/(2N(H2)+N(HI) is smaller than 10-5. Therefore, most of the DLA systems arise in warm (T > 3000 K) and diffuse neutral gas embedded in a strong UV flux. The very recent detection of HD molecules in a Damped Lyman-α system at z abs = 2.337 demonstrates the possibility to discuss the high redshift chemistry.

Keywords: Absorption lines; Molecular hydrogen; Observational cosmology; Quasars

Document Type: Research Article


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Publication date: July 1, 2002

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