The IceCube Neutrino Observatory is a cubic-kilometer Cherenkov telescope that operates at the South Pole. In 2013, IceCube discovered high-energy astrophysical neutrinos, and last year, it detected TeV neutrino emission from the nearby active galaxy NGC 1068. This discovery suggests that active galactic nuclei (AGN) could significantly contribute to the diffuse high-energy astrophysical neutrino flux. However, the absence of TeV gamma rays from NGC 1068 indicates that neutrino production occurs in the innermost region of the AGN. In this talk, I will give an overview of the most recent IceCube results on astrophysical neutrino sources and explore the possibility that the observed neutrino flux is produced in the cores of AGN, induced by accelerated cosmic rays in the accretion disk region. I will present a likelihood analysis based on eight years of IceCube data, searching for a cumulative neutrino signal from three AGN samples created for this work. The neutrino emission is assumed to be proportional to the accretion disk luminosity estimated from the soft X-ray flux. AGN are selected based on their radio emission, infrared color properties, and X-ray flux using the NVSS, AllWISE, ROSAT and XMM-SL2 catalogs. For the largest sample in this search, an excess of high-energy neutrino events with respect to an isotropic background of atmospheric and astrophysical neutrinos is found, corresponding to a post-trial significance of 2.60σ. If interpreted as a genuine signal with the assumptions of a proportionality of X-ray and neutrino fluxes, these results suggest that at 100 TeV, 27%-100% of the observed neutrinos arise from particle acceleration in the core of AGN.
Zoom link : https://cern.zoom.us/j/68399739111?pwd=SGErcHBQYmVLWFZTVE9jdm5xSmdEdz09
Indico : https://indico.in2p3.fr/event/29732/