Abstract
Existence of new gauge U(1) symmetry possessed by dark matter (DM) particles implies the existence of a new Coulomb-like interaction, which leads to Sommerfeld-Gamow-Sakharov enhancement of dark matter annihilation at low relative velocities. We discuss a possibility to put constraints on such dark forces of dark matter from the observational data on the gamma radiation in our Galaxy. Gamma-rays are supposed to originate from annihilation of DM particles in the small scale clumps, in which annihilation rate is supposed to be enhanced, besides higher density, due to smaller relative velocitiesvof DM particles. For possible cross sections, mass of annihilating particles, masses of clumps, and the contribution of annihilating particles in the total DM density we constrain the strength of new dark long range forces from comparison of predicted gamma-ray signal with Fermi/LAT data on unidentified point-like gamma-ray sources (PGS) as well as on diffuseγ-radiation. Both data on diffuse radiation and data on PGS put lower constraints on annihilation cross section at any dark interaction constant, where diffuse radiation provides stronger constraint at smaller clump mass. Density of annihilating DM particles is conventionally supposed to be defined by the frozen annihilation processes in early Universe.
Highlights
From the first articles revealing the indirect effects of the cold dark matter (CDM) in the form of heavy neutral leptons [1,2,3,4,5,6,7,8] or supersymmetric particles [7, 9, 10], indirect effects of dark matter annihilation had been the subject of intensive studies in the data on the cosmic rays (CR) and gamma radiation
The annihilation cross section can be enhanced at small relative velocities of DM particles, which are especially small in the lightest clumps, which are likely to be the most abundant
We have shown that DM clumps in vicinity of the Solar System could be observed as pointlike sources of the γ-radiation and they can partially explain unidentified γ-sources, registered by LAT
Summary
From the first articles revealing the indirect effects of the cold dark matter (CDM) in the form of heavy neutral leptons [1,2,3,4,5,6,7,8] or supersymmetric particles [7, 9, 10], indirect effects of dark matter annihilation had been the subject of intensive studies in the data on the cosmic rays (CR) and gamma radiation. Note that new interaction can lead to binding of DM particles into atomic-like states with their successive annihilation [41], or stable dark atoms in case of multicomponent (charge asymmetric) DM [41,42,43]. This effect, going beyond the scope of the present work, deserves separate consideration
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