  The active galaxy NGC 1068 was recently identified by the IceCube neutrino
observatory as the first known steady-state, extragalactic neutrino point
source, associated with about 79 events over ten years. We use the IceCube data
to place limits on possible neutrino self-interactions mediated by scalar
particles with mass between 1 - 10 MeV. We find that constraints on
flavor-specific $\nu_{\tau}$ self-interactions with low mediator masses are
comparable to constraints derived from the diffuse high-energy neutrino flux at
low energies, while constraints on flavor-universal self-interactions are less
restrictive than current bounds.

High Energy Physics - Phenomenology;High Energy Astrophysical Phenomena