  The effect of halo substructures on galaxy rotation curves is investigated in
this paper using a simple model of dark matter clustering. A dark matter halo
density profile is developed based only on the scale free nature of clustering
that leads to a statistically self-similar distribution of the substructures at
galactic scale. Semi-analytical method is used to derive rotation curves for
such a clumpy dark matter density profile. It is found that the halo
substructures significantly affect the galaxy velocity field. Based on the
fractal geometry of the halo, this self-consistent model predicts an NFW-like
rotation curve and a scale free power spectrum of the rotation velocity
fluctuations.
