  Polar ring galaxies are peculiar systems in which a gas rich, nearly polar
ring surrounds an early-type or elliptical host galaxy. Two formation scenarios
for these objects have been proposed: they are thought to form either in major
galaxy mergers or by tidal accretion of the polar material from a gas rich
donor galaxy. Both scenarios are studied through N-body simulations including
gas dynamics and star formation. Constraints on physical parameters are drawn
out, in order to determine which scenario is the most likely to occur. Polar
ring galaxies from each scenario are compared with observations and we discuss
whether the accretion scenario and the merging scenario account for
observational properties of polar ring galaxies. The conclusion of this study
is that the accretion scenario is both the most likely and the most supported
by observations. Even if the merging scenario is rather robust, most polar ring
galaxies are shown to be the result of tidal gas accretion events.
