First, they investigated whether any of the existing models can account for the detection of the two PeV events, now known as Bert and Ernie, and the simultaneous nondetection of higher-energy neutrinos. They found that the IceCube observation is inconsistent with all cosmogenic models at a confidence level greater than 90%, thus rejecting that the two PeV neutrinos in IceCube are cosmogenic particles.

[link to icecube.wisc.edu]