Can BL Lac emission explain the neutrinos above 0.2 PeV?

Understand

Multi-messenger astronomy can help to investigate the sources of the high-energy neutrinos observed by the high-energy neutrino telescope IceCube.

• We consider the hypothesis that the highest energy neutrinos are produced by BL Lacs, arguing that this is not contradicted severely by any known fact.
• We check the BL Lac hypothesis by searching for correlations between the through-going muon events of IceCube and the BL Lacs of the second catalog of Fermi-LAT (2FHL).
• We expect 10.2 $\pm$ 2.4 correlated events but we find that just 1 event has a BL Lac as counterpart.