Morphological Fractions of Galaxies in WINGS Clusters: revisiting the
  Morphology-Density Paradigm
  We present the Morphology-Density and Morphology-Radius relations (T-Sigma
and T-R, respectively) obtained from the WINGS database of galaxies in nearby
clusters. Aiming to achieve the best statistics, we exploit the whole sample of
galaxies brighter than MV=-19.5 (5,504 objects), stacking up the 76 clusters of
the WINGS survey altogether. Using this global cluster sample, we find that the
T-Sigma relation holds only in the inner cluster regions (R<1/3xR200), while
the T-R relation keeps almost unchanged over the whole range of local density.
A couple of tests and two sets of numerical simulations support the robustness
of these results against the effects of the limited cluster area coverage of
the WINGS imaging. The above mentioned results hold for all cluster masses
(X-ray luminosity and velocity dispersion) and all galaxy stellar masses (M).
The strength of the T-Sigma relation (where present) increases with increasing
M, while this effect is not found for the T-R relation. Noticeably, the
absence/presence of subclustering determines the presence/absence of the
T-Sigma relation outside the inner cluster regions, leading us to the general
conclusion that the link between morphology and local density is preserved just
in dynamically evolved regions. We hypothesize that some mechanism of
morphological broadening/redistribution operates in the intermediate/outer
regions of substructured (non relaxed) clusters, producing a strong weakening
of the T-Sigma relation.
