Speaker
Description
The astrophysical origins of extragalactic high-energy neutrinos remain an open question, although AGN are considered the strongest candidates. Yet, the specific emission sites within these accreting supermassive black hole systems, such as the relativistic jets versus the accretion disk or corona, are still debated. To investigate this, we cross-matched well localized neutrino events from the IceCat-1 catalog with a large, optically selected sample of quasars from the SDSS. Using radio data from the CLASS survey, we separated this population into flat-spectrum radio quasars (FSRQs) and radio-quiet (RQ) quasars. Our results show that while positional matches for RQ quasars are consistent with chance coincidences, FSRQs exhibit a significant correlation. Notably, for events at declinations above 20 degrees, the correlation reaches a significance of 4 sigma. For the most promising candidates, we extracted the neutrino spectra from IceCube data and determined their multiwavelength SEDs from public observations. These data are compared with theoretical models obtained through numerical simulations of the radiative interactions of cosmic-ray electrons and protons accelerated within the relativistic jet in a one-zone framework. These findings indicate that over 60% of IceCube’s astrophysical neutrinos could originate from FSRQs, providing possible evidence that the emission is mainly driven by relativistic jets rather than the accretion flow.