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Session 51 - Galaxy Evolution and the Intergalactic Medium.
Display session, Wednesday, June 10
The possible connection between High Velocity Clouds (HVCs) and Ly-\alpha absorbers seen in QSO spectra at low redshift, and the detectability of such cloud systems in other groups of galaxies, is investigated. HVCs are unlikely to be isolated phenomenta to our Galaxy. If they are infalling matter on galaxies, or groups of galaxies, such systems of other galaxies should appear as QSO Ly-\alpha absorbers at the corresponding galaxy redshifts. This should occur in the same way that Galactic HVCs appear as absorbers toward AGNs which happen to fall in the lines of sight to these clouds. We examine the possibility that the low z Ly-\alpha forest in QSO spectra is partly related to systems of HVCs in intervening groups of galaxies. The mass spectrum of HVCs, extrapolated from 21cm observations to lower column densities is consistent with the high incidence of Ly-\alpha absorbers at low z. The source function for the transient HVC gas can be assumed to be the dwarf galaxies in the groups.
Program listing for Wednesday