The Three-dimensional Structure of the Virgo Cluster Region from Tully-Fisher and H [CSC]i[/CSC] Data

(Abridged) The distances and HI contents of 161 spiral galaxies in the regionof Virgo cluster are used to gain insight into the complicated structure ofthis galaxy system. The 3D galaxy distribution has been inferred from qualitydistance estimates obtained by averaging distance moduli based upon the TFrelationship taken from eight published datasets previously homogenized.Previous findings that the spiral distribution is substantially more elongatedalong the line-of-sight than in the plane of the sky are confirmed by thecurrent data. In addition, an important east-west disparity in this effect hasbeen detected. The overall width-to-depth ratio of the Virgo cluster region isabout 1:4, with the most distant objects concentrated in the western half. Thefilamentary structure of the spiral population and its orientation are alsoreflected by the HI-deficient objects alone. The HI deficiency pattern shows acentral enhancement arising from galaxies that belong to the Virgo clusterproper. However, significant gas deficiencies are also detected outside themain body of the cluster in a probable group of galaxies at line-of-sightdistances 25-30 Mpc, as well as in various foreground galaxies. In the Virgoregion, the HI content of the galaxies then is not a straightforward indicatorof cluster membership.Comment: 35 pages, 7 figures. Accepted for publication by the Astronomical Journa