A search for time-dependent astrophysical neutrino emission with IceCube data from 2012 to 2017

TL;DR

This study conducted a comprehensive search for time-dependent astrophysical neutrino signals using IceCube data from 2012 to 2017, finding no significant evidence but setting limits on neutrino emission models.

Contribution

It provides the first all-sky, time-dependent neutrino search over multiple years with no prior source assumptions, and constrains models of neutrino emission from variable sources like blazars.

Findings

No significant neutrino signals detected.

Upper limits set on neutrino fluence from sources.

Constraints placed on hadronic emission models.

Abstract

High-energy neutrinos are unique messengers of the high-energy universe, tracing the processes of cosmic-ray acceleration. This paper presents analyses focusing on time-dependent neutrino point-source searches. A scan of the whole sky, making no prior assumption about source candidates, is performed, looking for a space and time clustering of high-energy neutrinos in data collected by the IceCube Neutrino Observatory between 2012 and 2017. No statistically significant evidence for a time-dependent neutrino signal is found with this search during this period since all results are consistent with the background expectation. Within this study period, the blazar 3C 279, showed strong variability, inducing a very prominent gamma-ray flare observed in 2015 June. This event motivated a dedicated study of the blazar, which consists of searching for a time-dependent neutrino signal correlated with the gamma-ray emission. No evidence for a time-dependent signal is found. Hence, an upper limit on the neutrino fluence is derived, allowing us to constrain a hadronic emission model.