Аннотация:
We present a range of unbroken power-law fits to the astrophysical-neutrino
spectrum consistent with the most recent published IceCube data at the
68 % confidence level. Assuming that the neutrinos originate in decays of
$\pi$-mesons, we estimate accompanying gamma-ray fluxes for various
distributions of sources, taking propagation effects into account.
We then briefly discuss existing experimental results constraining PeV to
EeV diffuse gamma-ray flux and their systematic uncertainties. Several
scenarios are marginally consistent both with the KASKADE and CASA-MIA
upper limits at $10^{15}$–$10^{16}$ eV and with the EAS-MSU tentative
detection at $\sim 10^{17}$ eV, given large systematic errors of the
measurements. Future searches for the diffuse gamma-ray background at
sub-PeV to sub-EeV energies just below present upper limits will give a
crucial diagnostic tool for distinguishing between the Galactic and
extragalactic models of the origin of the IceCube events.