Establishing the astrophysical origin of a signal in a neutrino telescope

Abstract

Recently the IceCube collaboration has reported the observation of 28 contained events with a visible energy in the interval between 60 TeV and 1.5 PeV, and has argued that this detection is evidence, with a statistical significance of more than four standard deviations, for the existence of an astrophysical neutrino flux that accounts for a large fraction of the events. In this work we analyze the arguments that allow to identify a component of astrophysical origin in the high energy neutrino flux separating it from atmospheric neutrinos. An astrophysical origin for a large fraction of the IceCube contained events is the simplest and most natural explanation of the data but, conservatively, an atmospheric origin cannot yet be entirely ruled out. This ambiguity should soon be resolved.