Use of ANTARES and IceCube data to constrain a single power-law neutrino flux

TL;DR

This study combines ANTARES and IceCube neutrino data to test the single power-law flux model, finding evidence for a second component due to excesses and statistical disfavouring of the single power-law hypothesis.

Contribution

It presents the first combined statistical analysis of ANTARES and IceCube data assuming a single power-law neutrino flux, revealing potential deviations from this model.

Findings

Combined data slightly reduces flux normalization and spectral index estimates.

Both datasets show excess in 40-200 TeV range, indicating a possible second component.

Single power-law model with IceCube's spectral index is statistically disfavored.

Abstract

We perform the first statistical combined analysis of the diffuse neutrino flux observed by ANTARES (nine-year) and IceCube (six-year) by assuming a single astrophysical power-law flux. The combined analysis reduces by a few percent the best-fit values for the flux normalization and the spectral index. Both data samples show an excess in the same energy range (40--200 TeV), suggesting the presence of a second component. We perform a goodness-of-fit test to scrutinize the null assumption of a single power-law, scanning different values for the spectral index. The addition of the ANTARES data reduces the $p$-value by a factor 2$\div$3. In particular, a single power-law component in the neutrino flux with the spectral index deduced by the six-year up-going muon neutrinos of IceCube is disfavored with a $p$-value smaller than $10^{-2}$.