학술논문

Probing the origin of cosmic rays with extremely high energy neutrinos using the IceCube Observatory
Document Type
article
Source
Physical Review D - Particles, Fields, Gravitation and Cosmology. 88(11)
Subject
astro-ph.HE
astro-ph.CO
hep-ex
Nuclear & Particles Physics
Astronomical and Space Sciences
Atomic
Molecular
Nuclear
Particle and Plasma Physics
Quantum Physics
Language
Abstract
We have searched for extremely high energy neutrinos using data taken with the IceCube detector between May 2010 and May 2012. Two neutrino-induced particle shower events with energies around 1 PeV were observed, as reported previously. In this work, we investigate whether these events could originate from cosmogenic neutrinos produced in the interactions of ultrahigh energy cosmic rays with ambient photons while propagating through intergalactic space. Exploiting IceCube's large exposure for extremely high energy neutrinos and the lack of observed events above 100 PeV, we can rule out the corresponding models at more than 90% confidence level. The model-independent quasidifferential 90% C.L. upper limit, which amounts to E2e+ν+ν=1.2×10-7 GeV cm-2 s-1 sr-1 at 1 EeV, provides the most stringent constraint in the energy range from 10 PeV to 10 EeV. Our observation disfavors strong cosmological evolution of the highest energy cosmic-ray sources such as the Fanaroff-Riley type II class of radio galaxies. © 2013 American Physical Society.