Effect of dark matter halo substructures on galaxy rotation curves

Abstract

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.