Repeated pattern of $\gamma$-ray flares in the blazar PKS 1502+106 coincident with the IC190730A neutrino event

TL;DR

This study investigates the potential link between repeating gamma-ray flare patterns in blazars and high-energy neutrino events, finding a statistically significant coincidence that suggests a possible physical connection.

Contribution

It provides the first statistical evidence supporting a connection between recurring gamma-ray flares in blazars and high-energy neutrino detections, using Monte Carlo simulations.

Findings

Probability of random coincidence is 1.56×10⁻³

Three neutrino events are coincident with blazar flare patterns

Supports the hypothesis of blazar jets as neutrino sources

Abstract

It has been demonstrated that at least 10 percent of the brightest blazars in the fourth Fermi-LAT catalog of $\gamma$-ray sources exhibit repeating patterns of $\gamma$-ray flares. These events may be associated with the presence of a non-uniform sheath surrounding a fast jet spine in some blazars. Theoretical models suggest that such a sheath could facilitate neutrino production in these structured jets. We aim to test the marginal statistical evidence previously reported for a connection between repeating patterns of $\gamma$-ray flares in blazars and high-energy neutrino events that are positionally consistent with these sources. We identified a repeating pattern of flares in the $\gamma$-ray light curve of the blazar PKS 1502+106, which lies within the 50\% uncertainty region of the IC190730A neutrino candidate event. This occurrence is combined with two other high-energy ($\ge 200$ TeV) neutrino events from ICECAT-1, which arrived in both positional and temporal coincidence with two blazars exhibiting ongoing repeating flare patterns. We conducted a Monte Carlo simulation to evaluate the likelihood of accidental coincidences between the repeating flare patterns and neutrino events, accounting for potential unrecognized systematic uncertainties in the arrival directions of the ICECAT-1 events. Our findings indicate the probability of a random coincidence, in both time and arrival direction for three high-energy neutrino candidates and three blazars with ongoing recurring patterns of $\gamma$-ray flares, is $1.56\times 10^{-3}$ ($3.2\sigma$).