The density profiles of Dark Matter halos in Spiral Galaxies
  In spiral galaxies, we explain their non-Keplerian rotation curves (RCs) by
means of a non-luminous component embedding their stellar-gaseous disks.
Understanding the detailed properties of this component (labelled Dark Matter,
DM) is one of the most pressing issues of Cosmology. We investigate the recent
relationship (claimed by Walker et al. 2010, hereafter W+10) between $r$, the
galaxy radial coordinate, and $V_h(r)$, the dark halo contribution to the
circular velocity at $r$, {\it a}) in the framework of the Universal Rotation
Curve (URC) paradigm and directly {\it b}) by means of the kinematics of a
large sample of DM dominated spirals. We find a general agreement between the
W+10 claim, the distribution of DM emerging from the URC and that inferred in
the (low luminosity) objects of our sample. We show that such a phenomenology,
linking the spiral's luminosity, radii and circular velocities, implies an
evident inconsistency with (naive) predictions in the $\Lambda$ Cold Dark
Matter ($\Lambda$CDM) scenario.
