Imprint of Multi-component Dark Matter on AMS-02

Abstract

The multi-component decaying dark matter (DM) scenario is investigated to explain the possible excesses in the positron fraction by PAMELA and recently confirmed by AMS-02, and in the total $e^+ +e^-$ flux observed by Fermi-LAT. By performing the $\chi^2$ fits, we find that two DM components are already enough to give a reasonable fit of both AMS-02 and Fermi-LAT data. The best-fitted results show that the heavier DM component with its mass 1.5 TeV dominantly decays through the $\mu$-channel, while the lighter one of 100 GeV mainly through the $\tau$-channel. As a byproduct, the fine structure around 100 GeV observed by AMS-02 and Fermi-LAT can be naturally explained by the dropping due to the lighter DM component. With the obtained model parameters by the fitting, we calculate the diffuse $\gamma$-ray emission spectrum in this two-component DM scenario, and find that it is consistent with the data measured by Fermi-LAT. We also construct a microscopic particle DM model to naturally realize the two-component DM scenario, and point out an interesting neutrino signal which is possible to be measured in the near future by IceCube.