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Martin A. Zwaan , Marc A. W. Verheijen , Frank H. Briggs, PASA, 16 (1), 100
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Next Section: Introduction | Contents Page: Volume 16, Number 1 |
The Hб I Column Density Distribution Function at z=0: the Connection to Damped Ly
Statistics
Martin A. Zwaan 1 - Marc A. W. Verheijen 2
Frank H. Briggs 1
1 Kapteyn Astronomical Institute, P.O. Box 800, 9700 AV Groningen, The Netherlands
zwaan, fbriggs@astro.rug.nl
2 National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801, U.S.A.
mverheij@aoc.nrao.edu
Abstract:
![$f(N_{\rm HI})$](/pasa/16_1/zwaan/paper/img1.gif)
. These high column densities compare to those measured in damped Ly
lines seen in absorption against background quasars. Although observationally rare, it appears that the bulk of the neutral gas in the Universe is associated with these damped Ly
systems. In order to obtain a good anchor point at z=0 we determine
in the local Universe by using 21cm synthesis observations of a complete sample of spiral galaxies. We show that
for damped Ly
systems has changed significantly from high z to the present and that change is greatest for the highest column densities. The measurements indicate that low surface brightness galaxies make a minor contribution to the cross section for Hб I, especially for
.
Keywords: galaxies: ISM -- galaxies: evolution -- quasars: absorption lines
- Introduction
- How to determine
at z=0?
- The Ursa Major Cluster
- The Column Density Distribution Function
- Contribution of Low Surface Brightness Galaxies
- Conclusions and Discussion
- References
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