Double pulses and cascades above 2 PeV in IceCube

TL;DR

This paper analyzes high-energy neutrino events detected by IceCube, focusing on double pulse signatures and cascades above 2 PeV to distinguish cosmic neutrino sources and production mechanisms, with implications for future observations.

Contribution

It introduces methods to identify tau neutrinos via double pulses and investigates cascade events above 2 PeV to differentiate neutrino production mechanisms.

Findings

Half of the double pulse signals are from neutrino energies already probed by IceCube.

Ten more years of data are needed to confidently detect double pulses.

Cascade observations can distinguish between pp and pγ sources within 50 years.

Abstract

IceCube collaboration has seen an unexpected population of high energy neutrinos compatible with an astrophysical origin. We consider two categories of events that can help to diagnose cosmic neutrinos: double pulse, that may allow us to clearly discriminate the cosmic component of tau neutrinos; cascades with deposited energy above 2 PeV, including events produced by electron antineutrinos at the Glashow resonance, that can be used to investigate the neutrino production mechanisms. We show that one half of the double pulse signal is due to the neutrinos spectral region already probed by IceCube. By normalizing to HESE data, we find that 10 more years are required to obtain 90% probability to observe a double pulse. The cascades above 2 PeV provide us a sensitive probe of the high energy tail of the neutrino spectrum and are potentially observable, but even in this case, the dependence on type of the source is mild. In fact we find that pp or p{\gamma} mechanisms give a difference in the number of cascades above 2 PeV of about 25 % that can be discriminated at 2{\sigma} in about 50 years of data taking.