Indirect Search for Dark Matter

Abstract

Possible dark matter candidates are reviewed as well as indirect search methods based on annihilation or decay channels of these particles. Neutralino is presently the best particle candidate and its annihilation produces high energy neutrinos, antiprotons, positrons and gamma-rays. To date, only upper limits on neutrino fluxes from the center of the Earth or the Sun, were established by different experiments. Antiprotons detected by the BESS collaboration, if issued from the follow up hadronization of the annihilation process, exclude neutralino masses higher than 100 GeV. The EGRET gamma-ray residual emission seen at high galactic latitudes above 1 GeV could be explained by neutralino annihilations if: i) the dark matter profile is "cored" and ii) the neutralino mass is < 50 GeV. Sterile neutrinos in the keV mass range are a possible candidate to constitute warm dark matter. These particles may provide an adequate free streaming mass able to solve "some" difficulties present in the cold dark matter scenario at small scales and could also explain the natal kick of pulsars. MeV particles, dubbed "light" dark matter, proposed to explain the extended 511 keV line emission from the galactic center will also be discussed.