Local Column Density Distribution Function from HI selected galaxies

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dc.creatorRyan-Weber, Emma
dc.creatorWebster, Rachel
dc.creatorStaveley-Smith, Lister
dc.date2001-07-27
dc.date.accessioned2026-07-07T01:59:27Z
dc.date.available2026-07-07T01:59:27Z
dc.descriptionThe cross-section of sky occupied by a particular neutral hydrogen column density provides insight into the nature of Lyman-alpha absorption systems. We have measured this column density distribution at z=0 using 21-cm HI emission from a blind survey. A subsample of HI Parkes All Sky Survey (HIPASS) galaxies have been imaged with the Australia Telescope Compact Array (ATCA). The contribution of low HI mass galaxies 10^7.5 to 10^8 M_solar is compared to that of M_star (10^10 to 10^10.5 M_solar) galaxies. We find that the column density distribution function is dominated by low HI mass galaxies with column densities in the range 3x10^18 to 2x10^20 cm^-2. This result is not intuitively obvious. M_star galaxies may contain the bulk of the HI gas, but the cross-section presented by low HI mass galaxies 10^7.5 to 10^8 M_solar is greater at moderate column densities. This result implies that moderate column density Lyman-alpha absorption systems may be caused by a range of galaxy types and not just large spiral galaxies as originally thought.
dc.description5 pages, including 1 figure. To appear in "Extragalactic Gas at Low Redshift" (ASP Conf. Series, Weymann Conf.)
dc.identifierhttps://arxiv.org/abs/astro-ph/0107522
dc.identifierhttp://arxiv.org/abs/astro-ph/0107522
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/3121
dc.subjectAstrophysics
dc.titleLocal Column Density Distribution Function from HI selected galaxies
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