Search Swinburne Research Bank
Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/58026
- The column density distribution function at z = 0 from HI selected galaxies
- Ryan-Weber, Emma V.; Webster, Rachel L.; Staveley-Smith, Lister
- We have measured the column density distribution function, f(N HI), at z = 0 using 21-cm HI emission from galaxies selected from a blind HI survey. f(NHI) is found to be smaller and flatter at z = 0 than indicated by high-redshift measurements of damped Lyman alpha (DLA) systems, consistent with the predictions of hierarchical galaxy formation. The derived DLA number density per unit redshift, dNDLA/dz =0.058, is in moderate agreement with values calculated from low-redshift QSO absorption line studies. We use two different methods to determine the types of galaxies which contribute most to the DLA cross-section: comparing the power-law slope of f(NHI) to theoretical predictions and analysing contributions to dNDLA/dz. We find that comparison of the power-law slope cannot rule out spiral discs as the dominant galaxy type responsible for DLA systems. Analysis of dNDLA/dz however, is much more discriminating. We find that galaxies with log MHI< 9.0 make up 34 per cent of dN DLA/dz; Irregular and Magellanic types contribute 25 per cent; galaxies with surface brightness -μ25 > 24 mag arcsec-2 account for 22 per cent and sub-L* galaxies contribute 45 per cent to dNDLA/dz. We conclude that a large range of galaxy types give rise to DLA systems, not just large spiral galaxies as previously speculated.
- Publication type
- Journal article
- Monthly Notices of the Royal Astronomical Society, Vol. 343, no. 4 (Aug 2003), pp. 1195-1206
- Publication year
- FOR Code(s)
- 0201 Astronomical and Space Sciences
- Absorption lines; Damped Lyman alpha; DLAs; Galaxies; ISM; Quasars
- Publisher URL
- Copyright © 2003 Royal Astronomical Society.
- Peer reviewed