Insider's view on PKS 1424+240, a bright TeV neutrino source

Recent years have brought increasing observational evidence for high-energy neutrinos coming from blazars. All-sky searches performed by the IceCube highlight PKS 1424+240 as the second strongest neutrino source with tens of neutrinos detected from its direction. We explore the central parsecs of the PKS 1424+240 jet using VLBI (Very Long Baseline Interferometry) observations and find an extremely large apparent opening angle. This indicates that its jet is directly pointed towards the Earth, we are effectively looking from inside the jet cone. Linear polarization structure reinforces this conclusion and unambiguously demonstrates a toroidal magnetic field. Blazars with such small viewing angles are rare, and their detailed studies are likely to bring more insights into neutrino production and beaming processes.