Ultra-High-Energy Cosmic Rays from Hypothetical Quark Novae

We explore the acceleration of ions in the quark nova (QN) scenario, in which a neutron star experiences an explosive phase transition into a quark star (born in the propeller regime). In this picture, two cosmic-ray components are isolated: one related to the randomized pulsar wind and the other to the propelled wind, both boosted by the ultrarelativistic QN shock. The latter component acquires energies 1015 eV < E < 1018 eV, while the former, boosted pulsar wind, achieves ultrahigh energies E > 1018.6 eV. The composition is dominated by ions present in the pulsar wind in the energy range above 1018.6 eV, while at energies below 1018 eV the propelled ejecta, consisting of the fallback neutron star crust material from the explosion, is the dominant one. Added to these two components, the propeller injects relativistic particles with Lorentz factors Γprop ~ 1-1000, later to be accelerated by galactic supernova shocks. The QN model appears to be able to account for the extragalactic cosmic rays above the ankle shown in the figure in this paper and to contribute a few percent of the galactic cosmic rays below the ankle. We predict a few hundred ultra-high-energy cosmic-ray events above 1019 eV for the Pierre Auger detector per distant QN, while some thousands are predicted for the proposed Extreme Universe Space Observatory (EUSO) and Orbiting Wide-angle Light collectors (OWL) detectors.