Extragalactic Blazar Diffuse Population Interpretation for the KM3-230213A event

On February 13, 2023, the KM3NeT/ARCA neutrino telescope detected an ultra-high-energy neutrino event, KM3-230213A, with an estimated energy in the hundreds of PeV range. In this study, we explore whether such a rare event can originate from a diffuse population of blazars. We simulate the neutrino and photon emission from blazar jets using the AM3 lepto-hadronic code, convolve the results with the Fermi-LAT blazar luminosity function, and evaluate the resulting diffuse flux. A likelihood analysis incorporating both KM3NeT and IceCube exposure data, as well as a gamma-ray background penalty from Fermi-LAT, allows us to constrain the parameter space of the baryonic loading and proton spectral index. We find that the KM3-230213A event could have been generated by a blazar diffuse flux, under physically motivated assumptions. This work demonstrates the strength of multi-messenger analyses and underlines the importance of joint neutrino observatory efforts in interpreting the high-energy sky.