High-energy rise in the cosmic-ray positron fraction: possible causes
TH Theory Conference Room (CERN)
TH Theory Conference Room
Recent PAMELA data seem to confirm previous evidence of an increase of the positron fraction in cosmic rays above an energy of E~7 GeV. In the first part of the talk, I will argue (based on general considerations rather than model-dependent fits to specific scenarios) that most likely this requires a primary galactic source of electron-positron pairs. In the second part of the talk, I will give a schematic overview of the possible models (both astrophysical ones and involving dark matter) proposed to explain the signature, emphasizing the importance of complementary constraints from other cosmic ray data, as well as specific signatures which may help in identifying the origin of the feature.