Neutrino flares of radio blazars observed from TeV to PeV

TL;DR

This study shows that high-energy neutrinos from radio blazars are often accompanied by lower-energy neutrino flares, strengthening the link between blazars and neutrino production and offering insights into their origin.

Contribution

It provides new evidence connecting high-energy neutrinos to blazar activity through correlated lower-energy neutrino flares, using IceCube data.

Findings

High-energy neutrinos (>200 TeV) are more likely with associated lower-energy flares.

Radio flux density correlates with likelihood of neutrino flares.

Chance correlation probability is very low ($3.6*10^{-4}$).

Abstract

Radio blazars have been linked both to individual high-energy neutrino events and to excesses in likelihood sky maps constructed from lower-energy neutrino data. However, the exact mechanism by which neutrinos are produced in these sources is still unknown. Here, we demonstrate that IceCube neutrinos with energies over 200 TeV, which were previously associated with bright radio blazars, are significantly more likely to be accompanied by flares of lower-energy events, compared to those lacking blazar counterparts. The parsec-scale core radio flux density of blazars, positioned within the error regions of energetic events, is strongly correlated with the likelihood of a day-scale lower-energy neutrino flare in directional and temporal coincidence with the high-energy event, reported by IceCube. The probability of a chance correlation is $3.6*10^{-4}$. This confirms the neutrino-blazar connection in a new and independent way, and provides valuable clues to understanding the origin of astrophysical neutrinos.