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We study the alignment of galaxies relative to their local environment inSDSS-DR8 and, using these data, we discuss evolution scenarios for differenttypes of galaxies. We defined a vector field of the direction of anisotropy ofthe local environment of galaxies. We summed the unit direction vectors of allclose neighbours of a given galaxy in a particular way to estimate this field.We found the alignment angles between the spin axes of disc galaxies, or theminor axes of elliptical galaxies, and the direction of anisotropy. Thedistributions of cosines of these angles are compared to the randomdistributions to analyse the alignment of galaxies. Sab galaxies showperpendicular alignment relative to the direction of anisotropy in a sparseenvironment, for single galaxies and galaxies of low luminosity. Most of theparallel alignment of Scd galaxies comes from dense regions, from 2...3 membergroups and from galaxies with low luminosity. The perpendicular alignment of S0galaxies does not depend strongly on environmental density nor luminosity; itis detected for single and 2...3 member group galaxies, and for main galaxiesof 4...10 member groups. The perpendicular alignment of elliptical galaxies isclearly detected for single galaxies and for members of < 11 member groups; thealignment increases with environmental density and luminosity. We confirm theexistence of fossil tidally induced alignment of Sab galaxies at low z. Thealignment of Scd galaxies can be explained via the infall of matter tofilaments. S0 galaxies may have encountered relatively massive mergers alongthe direction of anisotropy. Major mergers along this direction can explain thealignment of elliptical galaxies. Less massive, but repeated mergers arepossibly responsible for the formation of elliptical galaxies in sparser areasand for less luminous elliptical galaxies.

Alignment of galaxies relative to their local environment in SDSS-DR8