  In view of the observed flat rotation curves of spiral galaxies and motivated
by the simple fact that within newtonian gravity a stationary axisymmetric mass
distribution or dark matter vortex of finite extent readily displays a somewhat
flattened out velocity rotation curve up to distances comparable to the extent
of such a vortex transverse to the galaxy's disk, the possibility that such a
flattening out of rotation curves may rather be a manifestation of some
stationary axisymmetric space-time curvature of purely gravitational character,
without the need of some dark matter particles, is considered in the case of
the gravimagnetic dipole carrying opposite NUT charges and in the tensionless
limit of its Misner string, as an exact vacuum solution to Einstein's
equations. Aiming for a first assessment of the potential of such a suggestion
easier than a full fledged study of its geodesics, the situation is analysed
within the limits of weak field gravito-electromagnetism and nonrelativistic
dynamics. Thereby leading indeed to interesting and encouraging results.
