H_2-bearing damped Lyman-alpha systems as tracers of cosmological chemical evolution

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dc.creatorMurphy, M. T.
dc.creatorCurran, S. J.
dc.creatorWebb, J. K.
dc.date2003-10-15
dc.date2003-12-09
dc.date.accessioned2026-07-07T02:10:27Z
dc.date.available2026-07-07T02:10:27Z
dc.descriptionThe chemical abundances in damped Lyman-alpha systems (DLAs) show more than 2 orders of magnitude variation at a given epoch, possibly because DLAs arise in a wide variety of host galaxies. This could significantly bias estimates of chemical evolution. We explore the possibility that DLAs in which H_2 absorption is detected may trace cosmological chemical evolution more reliably since they may comprise a narrower set of physical conditions. The 9 known H_2 absorption systems support this hypothesis: metallicity exhibits a faster, more well-defined evolution with redshift than in the general DLA population. The dust-depletion factor and, particularly, H_2 molecular fraction also show rapid increases with decreasing redshift. We comment on possible observational selection effects which may bias this evolution. Larger samples of H_2-bearing DLAs are clearly required and may constrain evolution of the UV background and DLA galaxy host type with redshift.
dc.description6 pages, 1 figure, 1 table, v2: updated references, corrected typos, to appear in Recycling intergalactic and interstellar matter, IAU Symposium series, Vol. 217, 2004, edited by P.-A. Duc, J. Braine, E. Brinks
dc.identifierhttps://arxiv.org/abs/astro-ph/0310409
dc.identifierhttp://arxiv.org/abs/astro-ph/0310409
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/6744
dc.subjectAstrophysics
dc.titleH_2-bearing damped Lyman-alpha systems as tracers of cosmological chemical evolution
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