On the feasibility of constraining the triaxiality of the Galactic dark
  halo with orbital resonances using nearby stars
  It has recently been proposed that if the Galactic dark matter halo were
triaxial it would induce lumpiness in the velocity distribution of halo stars
in the Solar Neighbourhood through orbital resonances. These substructures
could therefore provide a way of measuring its shape. We explore the robustness
of this proposal by integrating numerically orbits starting from a realistic
set of initial conditions in dark halo potentials of different shape. We have
analysed the resulting velocity distributions in Solar neighbourhood-like
volumes, and have performed statistical tests for the presence of kinematic
substructures. Furthermore, we have characterized the particles' orbits using a
Fourier analysis. The local velocity distributions obtained are relatively
smooth, statistically consistent with being devoid of substructures even for a
dark halo potential with significant but plausible triaxiality. Although
resonances are indeed present and associated with specific regions of velocity
space, the fraction of stars associated to these is relatively minor. The most
significant imprint of the triaxiality of the dark halo is in fact, a variation
in the shape of the velocity ellipsoid with spatial location.
