Probing the connection between IceCube neutrinos and MOJAVE AGN

TL;DR

This study investigates the potential correlation between radio emissions from AGN and high-energy neutrinos detected by IceCube, using a decade of data and advanced statistical methods, but finds no significant correlation.

Contribution

It introduces a comprehensive stacking and time-dependent analysis of radio and neutrino data to probe AGN as neutrino sources, setting upper limits on their contribution.

Findings

No significant correlation found between AGN radio emissions and neutrinos.

Upper limits on AGN contribution to IceCube flux are approximately 3% and 9%.

Time-dependent analysis enhances statistical power over time-averaged methods.

Abstract

Active Galactic Nuclei (AGN) are prime candidate sources of the high-energy, astrophysical neutrinos detected by IceCube. This is demonstrated by the real-time multi-messenger detection of the blazar TXS 0506+056 and the recent evidence of neutrino emission from NGC 1068 from a separate time-averaged study. However, the production mechanism of the astrophysical neutrinos in AGN is not well established which can be resolved via correlation studies with photon observations. For neutrinos produced due to photohadronic interactions in AGN, in addition to a correlation of neutrinos with high-energy photons, there would also be a correlation of neutrinos with photons emitted at radio wavelengths. In this work, we perform an in-depth stacking study of the correlation between 15 GHz radio observations of AGN reported in the MOJAVE XV catalog, and ten years of neutrino data from IceCube. We also use a time-dependent approach which improves the statistical power of the stacking analysis. No significant correlation was found for both analyses and upper limits are reported. When compared to the IceCube diffuse flux, at 100 TeV and for a spectral index of 2.5, the upper limits derived are $\sim3\%$ and $\sim9\%$ for the time-averaged and time-dependent case, respectively.