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Jonathan Davies Cardiff University


Motivation
1. 2. 3. 4. Nearest large grouping of galaxies. A none `typical' environment - evolutionary processes. Luminosity function verse the HI mass function. Isolated HI clouds - the efficiency of galaxy (star) formation.

Data
Part of HIJASS - 4 beams with 12' resolution, 64 MHz bandpass with 1024 channels (12 km s-1). Used data only between 500 and 2500 km s-1. Scanned 4ox8o area (1/4 of cluster). Rms noise of 4 mJy beam-1 compared to HIJASS and HIPASS standard surveys of 13 mJy beam-1. Sensitivity is 5x107 M! at the distance of Virgo.


Object detection
Objects were detected using a combination of a by eye method and an automated routine.

Description of objects
To summarize - 28 detections of well known galaxies 4 new sources of which one is probably a normal galaxy behind M86. Other 3 no GOOD optical counterparts.


Comparison of Virgo HIJASS and HIPASS data


Jodrell pointed observations


Optical data


HI mass function


Distribution of velocities


Conclusions
1. (MHI/LB) much lower than HI selected field galaxies - anaemic spirals. 2. Velocity distribution - in-falling population ? 3. Mean column density 1020 atoms cm-2. 4. What is the relation between the cluster/field luminosity function and HI mass function ? 5. What debris from the galaxy formation process has or is assembling itself into the cluster ? Need to get below 107 M! to see if the mass function really turns over and to see if proposed high mass HVC exist in the cluster. 6. Reduce the ambiguity in optical identification, particularly important in the Virgo cluster.