A Time-Variability Test for Candidate Neutrino Sources Observed with IceCube

TL;DR

This paper introduces a new statistical method using the KS-test to detect and characterize time-variability in astrophysical neutrino sources observed with IceCube, independent of specific flare models.

Contribution

A novel KS-test based approach for identifying arbitrary time-variability in neutrino sources, complementing existing methods and applicable to various candidate sources.

Findings

Successfully applied to a small catalog of blazars.

Can distinguish variable from steady neutrino emission.

Provides a diagnostic tool for source characterization.

Abstract

Recent studies with IceCube have shown signs of a time-integrated flux of astrophysical neutrinos from point-like sources such as TXS 0506+056 and NGC 1068. Time-variability of this neutrino emission from TXS 0506+056 has been studied extensively by assuming a temporal profile of the possible flare(s) or searching for temporal neutrino correlation with other electromagnetic counterparts. However, experimental evidence of the temporal profile of an astrophysical neutrino signal, besides the TXS 0506+056 source, remains lacking. In this study, we present a new KS-test based method for investigating time-variability. This new method complements the existing time-dependent search methods with a test for arbitrary time-variability, independent of an assumed temporal profile or electromagnetic counterpart. Additionally, this method provides a diagnostic tool for characterizing point-like source candidates in IceCube by distinguishing variable from steady neutrino emission and we show results of applying this method to a small catalog of candidate blazars.