Halo dark matter and ultra-high energy cosmic rays

The decay of very heavy metastable relics of the Early Universe can produce ultra-high energy cosmic rays (UHECRs) in the halo of our own Galaxy. On distance scales of the order of the halo size, energy losses are negligible – no Greisen–Zatsepin–Kuzmin cutoff is expected. In this letter we show that, as a consequence of the hierarchical build up of the halo, this scenario predicts the existence of small scale anisotropies in the arrival directions of UHECRs. We also suggest some consequences of this scenario which will be testable with upcoming experiments, as Auger.