Speaker
Description
Jets launched by accreting supermassive black holes (SMBHs) are key to understanding how energy is extracted from compact objects and fed into their environments. How these jets form and where high-energy $\gamma$-rays are produced, in the so-called blazar zone, remain open questions. Competing scenarios place the $\gamma$-ray emission either close to the SMBH, within the broad-line region, or further downstream at parsec scales. Pinpointing the blazar zone is essential to link jet energetics to the accretion process and to establish conditions for multimessenger emission. Very long baseline interferometry (VLBI) offers a unique window into these inner-most jet regions, providing milliarcsecond resolution capable of tracing shocks, polarisation changes, and structural evolution. When combined with optical and X-ray polarimetry (utilising the Imaging X-ray Polarimetry Explorer; IXPE), $\gamma$-ray monitoring, and neutrino observations, VLBI enables directly connecting jet dynamics to high-energy phenomena. I will discuss using such synergistic observations between VLBI, neutrinos, and multiwavelength polarisation of selected blazars, which exhibited multimessenger flares and polarisation angle rotations. Our results unveil shock–shock interactions, the conditions suitable for hadronic emission, as well as the location of the $\gamma$-ray emission being at parsec scales away from the central engine. I will place these results in the broader context of our forthcoming Event Horizon Telescope studies, which will further probe high-energy emission from relativistic jets from supermassive black holes.