Binary Neutron Star Mergers as the Source of Ultrahigh Energy Cosmic Rays

Two perplexing features of UHECR data have eluded explanation up to now: (1) shock acceleration theory fails dismally in describing the observed spectrum; (2) the energy and composition of UHECRs are correlated, so that there is only a factor of a few spread in their ratio, E/Z, over two decades of energy. I will argue that both these features can be explained if UHECRs are produced in the magnetized turbulent outflow of binary neutron star (BNS) mergers. The BNS merger scenario naturally explains the observed peak value of E/Z. It also provides the first non-exotic explanation for the very highest energy UHECRs, surpassing 100 EeV: that these CRs originated as r-process nuclei. Extremely high energy neutrinos, with E> 10 PeV, are produced by interactions of UHECRs near their source; thus a striking prediction of this proposal is that every EHE neutrino is accompanied by a gravitational wave burst. This will be tested with next-generation neutrino and GW detectors. Other consequences and tests of the proposal will be discussed.