Dark matter caustics and the enhancement of self-annihilation flux

International audienceCold dark matter haloes are populated by caustics, which are yet to be resolved in N-body simulations or observed in the Universe. The secondary infall model provides a paradigm for the study of caustics in typical haloes assuming that they have had no major mergers and have grown only by smooth accretion. This is a particular characteristic of the smallest dark matter haloes of about 10^{-5}~M_\odot , which although atypical contain no substructures and could have survived until now with no major mergers. Thus using this model as the first guideline, we evaluate the neutralino self-annihilation flux for these haloes. Our results show that caustics could leave a distinct sawteeth signature on the differential and cumulative fluxes coming from the outer regions of these haloes. The total annihilation signal from the regions away from the centre can be boosted by about 40%