Boosting indirect detection of a secluded dark matter sector

Abstract: Dark Matter (DM) residing in a secluded sector with suppressed portal interaction could evade direct detections and collider searches. The indirect detections provide the most robust probe to this scenario. Depending on the structure of the dark sector, novel DM annihilation spectra are possible. The dark shower is a common phenomenon for particles in the dark sector which take part in strong interactions and are boosted. In terms of simplified two-component DM models with vector portal interaction and pseudoscalar portal interaction, we study the dark showering effects for DM indirect detection. In those models, the heavier DM component which dominates the relic density annihilates into boosted lighter species. Together with the large coupling through which the lighter DM annihilates away in the early universe, the showered spectra provide as the smoking gun for the DM existence. Considering bounds obtained by the AMS-02 positron data and Fermi-LAT measurement of gamma-ray from the dwarf galaxies, we find the dark shower could open a new region of sensitivity that can not be probed before.