On the Orbital Velocity of Isolated Galaxy Pairs: a test of gravity in
  the low acceleration regime
  The dynamics of isolated galaxy pairs represents an important tool to
investigate the behavior of gravity in the low acceleration regime. Statistical
analysis of a large sample of galaxy pairs led to the noticeable discovery of a
region of preferred 3-dimensional velocities centered at $\sim 150$ km/s and
$\sim 100$ km/s wide, a feature hard to justify in the context of numerical
simulations of cosmological structure formation. It is shown here that such a
feature is expected within the framework of the Modified Newtonian Dynamics,
which, however, predicts it to be centered at $\sim$ 170 Km/s.
