1999MNRAS.303...50G

We investigate the orientations of the galactic axes within 18 selected clusters, substructures of the Local Supercluster. For every cluster we map the parameter Δ₁₁ describing the alignment of the galactic axes with respect to a chosen cluster pole, divided by its formal error σ (Δ₁₁) [s ≡ Δ₁₁/ σ (Δ₁₁)]. The cluster pole coordinates change along the entire celestial sphere. The resulting maps are analysed for correlations of their maxima with directions from the cluster centre to (i) the derived `physical' cluster poles, (ii) the Local Supercluster centre, (iii) the Virgo A centre and (iv) the Earth, i.e. along the line of sight (≡ LOS). The strong maxima – with one exception – exist only for non-spiral (NS) subsamples, with the maximum well correlated with the LOS direction. Another of the studied directions may occur close to the maximum only if these directions are close to the LOS and they do not correlate with other features visible on the maps. For clusters with a clearly defined maximum of s below 3.0 the conclusion generally does not change. For the spiral (S) subsamples the maps are usually at the random noise level. In these cases a weaker, but still existing correlation with the LOS is observed and no other evident correlations are noted. We conclude that a strong systematic effect, generated by the process of deprojection of a galactic axis from its optical image, is present in the catalogue data. It can mask any weak alignment existing in the analysed clusters. With the use of a simple model for the systematic effect we are able to reproduce the main characteristic features of the maps for non-spiral galaxies. We note, however, that a few clusters show significant differences with respect to this model.