Speaker
Description
Blazars are promising candidate sources of high-energy astrophysical neutrinos, but the location of neutrino production in blazars remains uncertain. In our study (Kun et al. 2026), we investigate the temporal connection between a suspected IceCube neutrino flare and the gamma-ray and radio emission of the blazar GB6 J1542+6129. We performed a likelihood analysis of 17 years of Fermi-LAT data and constructed a gamma-ray light curve to investigate the temporal relationship between the gamma-ray emission, the suspected neutrino flare, and the VLBI core activity. The analysis combines these gamma-ray observations with approximately 14 years of Very Long Baseline Interferometry (VLBI) data from the MOJAVE programme. The suspected neutrino flare precedes both a gamma-ray flare and an increase in the inferred Doppler factor of the VLBI core by up to approximately one year. Furthermore, the duration of the subsequent gamma-ray activity is comparable to that of the neutrino flare. These temporal relationships are consistent with a scenario in which neutrinos originate in a compact, photon-rich region upstream of the parsec-scale radio core, while a propagating disturbance subsequently enhances the electromagnetic emission as it reaches the radio core. This study demonstrates the potential of time-domain multimessenger observations to constrain the location of neutrino production in active galactic nuclei.