  According to high resolution cold dark matter (CDM) simulations, large
virialized halos are formed through the constant merging of smaller halos
formed at earlier times. In particular, the halo of our Galaxy may have
hundreds of dark matter clumps. The annihilation of dark matter particles such
as the neutralino in these clumps generates $\gamma$-ray fluxes that can
potentially be detected by future experiments such as GLAST. We find that,
depending on the parameters of the clump density profile and on the
distribution of clumps in the Galactic halo, the contribution to the diffuse
$\gamma$-ray background from clumps can constrain the properties of neutralinos
such as the mass and annihilation cross section. We model the density profile
of clumps by three representative dark matter profiles: singular isothermal
spheres (SIS), Moore profiles, and Navarro, Frenk and White (NFW) density
profiles and calculate the spectrum and angular distribution in the sky of the
$\gamma$-ray flux due to neutralino annihilation in the clumpy halo of the
Galaxy. The calculations are carried out in the context of two different
scenarios for the distribution of clumps in the Galaxy and their
concentrations, which result in very different conclusions.
