Fermi Gamma-ray Space Telescope

3LAC counterparts to IceCube neutrinos above 100 TeV

Felicia Krauss
(K. Deoskar, M. Kreter, M. Kadler, K. Mannheim, J. Wilms)


In light of the recent tantalizing coincidences between outbursts of the blazars PKS 1424-418 and TXS 0506+056 and two IceCube neutrino events, we study all 179 3LAC blazars consistent with HESE IceCube neutrinos above 100 TeV. We construct the high-energy spectral energy distribution (SED). Adopting the IceCube neutrino spectrum of the extraterrestrial excess flux, and assuming that the neutrino and photon integrated energy fluxes are equal, we compute the expected neutrino event numbers. We emphasize, that the calorimetric photon energy fluxes obtained by integrating over the SED differ by a large margin from the Fermi-LAT fluxes alone. The resulting numbers are in good agreement with the observed neutrino events and constrain the hadronicness of blazars, suggesting that blazars contribute largely at these energies. In particular, we note that the non-detection of many gamma-ray bright blazars is still in agreement with the hadronic blazar model.