Matteo Cerruti (APC Paris)

Neutrinos from super-massive black holes: constraints on radiative models and the need for mixed, multi-zone scenarios

Accreting super-massive black holes (also known as Active Galactic Nuclei, AGNs) are prime candidates for cosmic-ray acceleration in the Universe, and hence for high-energy neutrino production. I will review leptonic and hadronic emission frameworks, highlighting why purely leptonic models sometimes fail and where hadrons naturally enter through proton-photon and proton-proton channels and pair-cascade development. Using TXS 0506+056 as a benchmark, I will discuss how lepto-hadronic models with external photon targets are now favored in the community. The 2014/15 TXS 0506+056 neutrino episode, lacking a gamma-ray counterpart, points toward physically distinct neutrino and gamma-emitting zones. The evidence for neutrino emission from NGC 1068 also favors structured and obscured multi-zone models. Finally, I will present a code-comparison effort between several hadronic codes in the literature, showing robust spectral shapes but a 40% spread in normalization.