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Molecular Hydrogen in the High Redshift Damped Ly-α Systems:

Published online by Cambridge University Press:  30 March 2016

R. Srianand ,
P. Petitjean ,
C. Ledoux  and
G. Ferland
R. Srianand
Affiliation:
IUCAA, Postbag 4, Ganeshkhind, Pune 411007, India
P. Petitjean
Affiliation:
Institut d’Astrophysique de Paris – CNRS, 98bis Boulevard Arago, F-75014 Paris, France
C. Ledoux
Affiliation:
European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago, Chile
G. Ferland
Affiliation:
Department of Physics and Astronomy, University of Kentucky, 177 Chemistry/Physics Building, Lexington, KY 4050

Abstract

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This review talk summarizes the main results obtained from the just completed survey of molecular hydrogen in damped Lyman-a systems (DLAs). Preliminary results based on modeling ionization conditions and chemical network is also presented. The presence of H2 and fine-structure lines of C 1 in 13-20% of DLAs allow one to investigate the physical conditions using the techniques that are commonly used in the studies of the Galactic ISM. It is shown that the DLAs with H2 trace regions with higher density, lower temperature, moderate to high dust depletion, and local star-formation. Absence of H2 in DLAs with moderate dust depletion could just be a simple consequence of lower densities in the systems.

Type
I. Joint Discussions
Information
Highlights of Astronomy , Volume 13 , 2005 , pp. 833 - 838
Copyright
Copyright © Astronomical Society of Pacific 2005

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