Abstract: High-energy neutrinos are solely produced in interactions of cosmic rays with ambient matter or photon fields and are therefore a smoking-gun signature for hadronic acceleration.
A diffuse flux of cosmic neutrinos was first discovered by the cubic-kilometer-sized IceCube detector located at the South Pole in 2013. I will present the ongoing search for the origin of those neutrinos and discuss promising candidate sources including the gamma-ray blazar TXS 0506+056, the tidal disruption event AT2019dsg and the nearby Seyfert galaxy NGC 1068.