Speaker
Description
Accreting systems in the centres of Active Galactic Nuclei (AGN) produce highly collimated relativistic jets.Magnetohydrodynamic simulations show that strong magnetic fields, twisted by the differential rotation of central black hole, play dynamically important role in these processes. Due to the dependence of the polarized radiation transfer coefficients on elementary composition and energy spectrum of magnetized plasma, polarimetric observations are an ideal tool for tracing the magnetic fields and probing properties of internal and external media of AGN jets. To date, polarimetric VLBI technique allows obtaining the highest angular resolution and thus spatially resolving polarization structure of relativistic jets. Moreover, Faraday rotation measures deliver the least model dependent information on jet physical properties. The feasibility of space polarimetric interferometric observations has been successfully demonstrated by VSOP (VLBI Space Observatory Programme) mission in early 2000s, that included a satellite antenna in near-Earth orbit. Recently, successful polarization observations of extragalactic objects by the RadioAstron project were carried out. The mission featured a 10-m space antenna orbiting the Earth in a high elliptical orbit, allowing detections of AGNs at projected baselines up to 28 Earth diameters. These space-VLBI polarization observations revealed the innermost compact jet regions, making possible to improve our understanding of magnetic fields and to address the physics of AGN jets. In this talk, I will discuss recent VLBI and space-VLBI polarimetric studies of Active Galactic Nuclei jets.
