Presentation #439.02 in the session “Relativistic Astrophysics”.
The neutrino sky as seen at ten years by the omni-directional South Pole telescope, IceCube, exhibits a number of inconsistencies with widely accepted theoretical expectations for astrophysical neutrino production. Nominally, hadronically driven sources (e.g. active galactic nuclei (AGN), star-forming galaxies (SFG), ultra-luminous infrared galaxies), might act as production sites for neutrinos. An apparent absence of such sources prompts a reassessment of the assumed production and transport physics. The results of a new study testing a novel neutrino production mechanism are discussed. Specifically, the possibility of neutrino production through line-of-sight cosmic ray interactions with extragalactic background light (EBL) has been accounted for in modeling signal expectations for AGN and star-forming galaxy populations with three years of public IceCube data. This weighting scheme predicts a source flux inversely proportional with distance, increasing the expected contributions of distant sources and level of isotropy. Upper limits on the associated AGN and SFG all-sky flux from this model, and other standard physical models, are constrained to percent and sub-percent levels of the reported IceCube diffuse astrophysical flux. In light of other characteristic diffuse spectral features observed by IceCube, and the singly detected point source, TXS 0506+056, increasing evidence in favor of an exotic physics explanation is highlighted.