The principal conclusion from this survey is that no new HI-rich systems (LSB galaxies or intergalactic clouds) were discovered. The previous deep optical surveys in the CVn group region (BTS), followed by 21 cm line observations, have succeeded in cataloging all the galaxies that the current Nançay survey detected. With the follow-up observations (and their non-confirmations) of all events, the survey is complete to HI masses above throughout the CVn groups. This limit is most strict for the high mass range. This corroborates the early conclusions made by Fisher & Tully (1981a) from their blind HI-survey in the M 81-group region with a limiting sensitivity a factor two higher compared to the here performed HI-survey.
The logical consequence is that intergalactic clouds and unseen gas-rich galaxies can form a population amounting to at most 1/30 the population in optically cataloged large galaxies. This result is highly consistent with earlier work (Zwaan et al. 1997; Briggs 1997b; Briggs 1990).
For lower HI masses, the current Nançay Survey was insufficiently sensitive for detections throughout the groups. The depth of the experiment drops as kpc, so that the volume in which small masses ()could be detected is small and does not extend to include both CVn groups.
The HI-defined sample obtained here, which is complete to throughout the CVn and Coma groups is well described by the Zwaan et al. (1997) HI mass function with a slope of and a scaling factor of 4.5.
The Unité Scientifique Nançay of the Observatoire de Paris is associated as Unité de Service et de Recherche (USR) No. B704 to the French Centre National de Recherche Scientifique (CNRS). The Observatory also gratefully acknowledges the financial support of the Région Centre in France. While at the Observatoire de Paris (Meudon), the research by RCKK was supported with an EC grant. BB thanks the Swiss National Science Foundation for financial support. This research has made use of the Lyon-Meudon Extragalactic Database (LEDA) supplied by the LEDA team at the CRAL-Observatoire de Lyon (France), as well as of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
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