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M.A. Zwaan (University of Melbourne), L. Staveley-Smith (Australia Telescope National Facility), M.J. Meyer, R.L. Webster (University of Melbourne), HIPASS Team
We present a new and accurate measurement of the density of cool baryons in the local Universe. This measurement is based on the HI mass function of galaxies, calculated from the HIPASS survey, a blind 21cm HI survey of the southern sky. The HIPASS survey has resulted in the largest sample of HI selected galaxies, and is ideally suited to measure the HI mass function of galaxies with unprecedented accuracy. The HIPASS sample enables for the first time a study of the dependence of local galaxy density, morphology, and optical surface brightness on the shape of the HI mass function.
The mass density of neutral gas in the local universe is found to be approximately five times lower than that at redshifts 2-4, indicating strong evolution of the neutral gas. Low surface brightness galaxies are found to contribute very little to neutral gas mass density.
The author(s) of this abstract have provided an email address for comments about the abstract: mzwaan@ph.unimelb.edu.au
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.