Speaker
Description
We are currently at the dawn of a new era in multi-messenger astrophysics. Imaging air-Cherenkov telescopes such as MAGIC, H.E.S.S., and VERITAS have already detected around 90 active galactic nuclei (AGN) at TeV energies, while neutrino observatories like IceCube and KM3NeT have identified several high-energy neutrinos likely associated with AGN. A key open question remains: where in the jet, and through which physical mechanisms, are TeV gamma rays and neutrinos produced?
Very Long Baseline Interferometry (VLBI) is a uniquely powerful tool to address this question, as it allows us to resolve AGN jets down to sub-milliarcsecond scales and directly probe the regions where extreme particle acceleration may occur. Using cm- and mm-VLBI observations with the VLBA, EVN, GMVA, and EHT, we can resolve the innermost jet regions of TeV-detected and neutrino-candidate blazars. This enables us to identify characteristic jet structures and trace structural changes potentially linked to high-energy activity.
I will present new results on a sample of TeV-emitting AGN, and the neutrino-candidate blazars PKS 0215+015 and TXS 0506+056, combining dedicated VLBI observations with long-term single-dish monitoring from the Effelsberg 100-m telescope. By linking radio variability and jet morphology to very-high-energy activity, this multimessenger approach also sets the stage for future synergies with the SKA and the ngVLA, which will greatly enhance such studies through their superior sensitivity and resolution.
| Talk category | Plenary |
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