Ultrahigh energy neutrinos from superconducting cosmic strings

Abstract

Superconducting cosmic strings naturally emit highly boosted charge carriers from cusps. This occurs when a cosmic string or a loop moves through a magnetic field and develops an electric current. The charge carriers and the products of their decay, including protons, photons, and neutrinos, are emitted as narrow jets with opening angle θ∼1/γc, where γc is the Lorentz factor of the cusp. The excitation of electric currents in strings occurs mostly in clusters of galaxies, which are characterized by magnetic fields B∼10−6 G and a filling factor fB∼10−3. Two string parameters determine the emission of the particles: the symmetry breaking scale η, which for successful applications should be of order 109–1012 GeV, and the dimensionless parameter ic, which determines the maximum induced current as Jmax=iceη and the energy of emitted charge carriers as ϵX∼icγcη, where e is the electric charge of a particle. For the parameters η and B mentioned above, the Lorentz factor reaches γc∼1012 and the maximum particle energy can be as high as γcη∼1022 GeV. The diffuse fluxes of ultrahigh energy neutrinos are close to the cascade upper limit, and can be detected by future neutrino observatories. The signatures of this model are: very high energies of neutrinos, in excess of 1020 eV; correlation of neutrinos with clusters of galaxies; simultaneous appearance of several neutrino-produced showers in the field of view of very large detectors, such as JEM-EUSO; and 10 TeV gamma radiation from the Virgo cluster. The flux of ultrahigh energy protons from cusps may account for a large fraction of the observed events at the highest energies.

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