Anisotropy of dark matter annihilation with respect to the Galactic plane

Abstract

We describe the anisotropy of dark matter clump distribution caused by tidal destruction of clumps in the Galactic disk. A tidal destruction of clumps with orbit planes near the disk plane occurs more efficiently as compared with destruction of clumps at near-polar orbits. A corresponding annihilation of dark matter particles in small-scale clumps produces the anisotropic gamma-ray signal with respect to the Galactic disk. This anisotropy is rather small, 9%, and superimposed on that due to off-centering position of the Sun in the Galaxy. The anisotropy of annihilation signal with respect to the Galactic disk provides a possibility to discriminate dark matter annihilation from the diffuse gamma-ray backgrounds of other origin.