Spencer Klein

Where do cosmic neutrinos come from?

Over the past 2 years, IceCube's observation of a diffuse flux of astrophysical neutrinos with energies above 50 TeV has solidified, with analyses of through-going muons providing a nearly independent confirmation of the signal observed with contained events. The high diffuse flux should, in principle, make it easy to pin down the sources of these neutrinos. However, we have not been able to associate these neutrinos with any astrophysical objects or classes of objects, and we are not able to set limits eliminating or disfavoring most of the more popular source hypotheses. In this talk, I will review the newest evidence for astrophysical neutrinos, and discuss current limits on individual sources and source models.