Search for directional correlations of high-energy neutrinos in IceCube with astronomical source catalogs

The IceCube Neutrino Observatory has measured a diffuse astrophysical muon neutrino flux with good directional information. So far, dedicated searches for astrophysical neutrino point sources have not been successful, and the production sites of astrophysical neutrinos remain undetermined. Nevertheless, there are several theoretical models predicting classes of extra-galactic sources which would be abundant, but too faint to be detected individually. A cross-correlation analysis of neutrino arrival directions with astronomical source catalogs is presented. An example is the the NVSS catalog of radio sources. The analysis is based on the multipole expansion coefficients of the neutrino sky map that are compared to the expansion coefficients of the catalog.