Search for extended sources of neutrino emission with 7 years of IceCube data

The IceCube Neutrino Observatory has demonstrated the existence of an astrophysical high-energy neutrino flux with a significance exceeding 7σ. Nevertheless, the observed astrophysical neutrino flux shows no clear association with any known source class so far. The most recent searches for point sources using seven years of data from IceCube have found no significant clustering of neutrino events nor correlation with preselected sources. However not all potential neutrino sources would appear point-like, and it is therefore important to widen the search to different source topologies. The high-energy gamma-ray and cosmic-ray skies show clear indications of extended structures. In the case of cosmic-ray interactions in these environments, both gamma-ray and neutrino emission are expected, and the detection of this neutrino flux would represent unambiguous proof of the hadronic nature of the sources. In addition, an extended source search could improve sensitivity to several point sources located close together in space, for example the Cygnus region, even if the individual fluxes are too low to be detected separately. Here we present the results of an extended source analysis with seven years of IceCube data. Because the extensions of potential sources are not always known a priori, five different extensions have been considered, from 1° to 5°. All the five maps are consistent with the background-only hypothesis.SCOPUS: cp.pSCOPUS: cp.p