Gamma-ray evidences of the dark matter clumps
  We discuss the possibility of identification of point-like gamma-ray sources
(PGS) with small scale dark matter (DM) clumps in our Galaxy. Gamma-rays are
supposed to originate from annihilation of DM particles in the clumps, where
annihilation rate is supposed to be enhanced, besides higher density, due to
smaller relative velocities $v$ of DM particles. We parameterized the
annihilation cross section $\sigma_\text{ann}(v)$ in the form of an arbitrary
power law dependence on the relative velocity $v$ with/without factor of
Sommerfeld-Gamow-Sakharov, implying existence of a new Coulomb-like
interaction. Adopting different parameters of cross section and clump,
satisfying condition $\Omega\lesssim 0.2$ on density of DM particles of
question, they are constrained from comparison with Fermi/LAT data on
unidentified PGS as well as on diffuse $\gamma$-radiation; results are applied
to concrete DM candidates. Such analysis is found to be sensitive enough to
existing uncertainty in the density profiles of DM in the clump what can
provide a tool for their test. Also we discuss possibilities when
gamma-radiating clump changes visibly its position on celestial sphere and it
is seen as a spatially extended gamma-source (EGS), what can be probed in
future experiments like Gamma-400.
