  We present an analysis of high resolution HI data of the dwarf galaxy DDO 47,
aimed at testing the hypothesis that dark halo triaxiality might induce
non-circular motions resulting in rotation curves best fitted by cored halos,
even if the dark matter halo is intrinsically cuspy. This hypothesis could be
invoked in order to reconcile the predictions of the standard LambdaCDM theory
with the rotation curves of disk galaxies. DDO 47 is an ideal case to test this
hypothesis because it has a very regular velocity field, its rotation curve is
best fitted by a cored halo and a NFW halo is inconsistent with the data. We
analysed the velocity field through the higher-order harmonic terms in order to
search for kinematical signatures of alleged non-circular motions needed to
"hide" a cusp: the result is that globally non-circular motions are at a level
of 2-3 km/s, and they are more likely to be associated to the presence of some
spiral structure than to a global elongated potential (e.g. a triaxial halo).
These non-circular motions are far from being sufficient to account for the
discrepancy with the LambdaCDM predictions. We therefore conclude that the dark
matter halo around the dwarf galaxy DDO 47 is truly cored and that a cusp
cannot be hidden by non-circular motions.
