What IceCube data tell us about neutrino emission from star-forming galaxies (so far)

Understand

Very recently, the IceCube Collaboration reported a flux of neutrinos in the energy range 50 TeV < E_\nu < 2 PeV, which departs from expectations from atmospheric background at the 5.7\sigma level.

• This flux is in remarkable agreement with the expected diffuse flux of neutrinos from starburst galaxies, and the 3 highest energy events have uncertainty contours encompassing some of such systems.
• These events, all of which have well-measured energies above 1 PeV, exhibit shower topologies, for which the angular resolution is about 15^\circ.
• Due to this angular uncertainty and the a posteriori nature of cuts used in our study it is not possible to assign a robust statistical significance to this association.