  Identifying the astrophysical sources responsible for the high-energy cosmic
neutrinos has been a longstanding challenge. In a previous work, we report
evidence for a spatial correlation between blazars from the 5th Roma-BZCat
catalog and neutrino data of the highest detectable energies, i.e. >0.1 PeV,
collected by the IceCube Observatory in the southern celestial hemisphere. The
statistical significance is found at the level of 2 x 10^{-6} post-trial. In
this work we test whether a similar correlation exists in the northern
hemisphere, were IceCube is mostly sensitive to <0.1 PeV energies. We find a
consistent correlation between blazars and northern neutrino data at the
pre-trial p-value of 5.12 x 10^{-4}, and a post-trial chance probability of
6.79 x 10^{-3}. Combining the post-trial probabilities observed for the
southern and northern experiments yields a global post-trial chance probability
of 2.59 x 10^{-7} for the genuineness of such correlation. This implies that
the spatial correlation is highly unlikely to arise by chance. Our studies push
forward an all-sky subset of 52 objects as highly likely PeVatron extragalactic
accelerators.
