A strong recollimation shock far from the core of the radiogalaxy 3C120

Which could be the mechanism for the production of moving and stationary components in AGN jets? How is it possible that a stationary component appears to be composed by subcomponents moving at superluminal speeds?

The AGNs are a special class of galaxies that show an unusual amount of emission. The responsible of this emission is a supermassive black hole () that accretes matter from a hot rotating disk, leading to the formation of ultra luminous jets that transport material at speeds very close to that of light to distances far beyond the size of the host galaxy. These jets often show standing or sub/superluminal structures (knots), but what is the production mechanism for these knots is still unclear.

In 2010 we detected for the first time an extended stationary component (C80) located at 140 pc from the core of the radiogalaxy 3C120 presenting an unusually large emission which triggered our attention and we decided to study it in more detail.

In a recent work, we analyzed the total and polarized emission of C80 with high sensitivity and high resolution images (VLBA at 5 GHz) and what we observe is in agreement with numerical modeling leading us to conclude that C80 corresponds to a conical recollimation shock in the jet of 3C120.