  The origin of the diffuse astrophysical neutrino flux measured by the IceCube
Observatory remains largely unknown. Although NGC 1068 and TXS 0506+056 have
been identified as potential neutrino sources, the diffuse flux of neutrinos
must have additional sources that have not yet been identified. Here we
investigate potential correlations between IceCube's neutrino events and the
Fermi and MOJAVE source catalogs, using the publicly-available IceCube data
set. We perform three separate spatially-dependent, energy-dependent, and
time-dependent searches, and find no statistically significant sources outside
of NGC 1068. We find that no more than 13% of IceCube's neutrino flux
originates from blazars over the whole sky. Then, using an energy-dependent
likelihood analysis, the limit on neutrinos originating from blazars reduces to
9% in the Northern hemisphere. Finally, we set limits on individual sources
from the MOJAVE radio catalog after finding no statistically significant
time-flaring sources.
