Speaker: Dr. Nicholas MacDonald (Max Planck Institute for Radio Astronomy, Germany)
Location: Van de Hulst Auditorium
Extragalactic jets are highly collimated beams of relativistic plasma that emanate from the centers of Active Galactic Nuclei (AGN). Despite decades of dedicated observation and study the underlying plasma composition of these relativistic outflows remains largely unknown. The polarized emission emanating from relativistic jets, however, can now be imaged on micro arcsecond scales using Global mm-wave Very Long Baseline Interferometry (VLBI). These polarimetric observations provide us with a powerful probe of the underlying nature of the jet plasma. In parallel to this observational advance, modern computational resources have allowed for increasingly sophisticated numerical jet simulations. Relativistic magnetohydrodynamic (RMHD) jet models are able to reproduce many of the observed macroscopic features of these plasma flows (e.g., recollimation shocks, jet sheaths & spines, bow shocks, & enshrouding jet cocoons). The radio synchrotron emission detected by VLBI arrays, however, is a by-product of the non-thermal physics occurring within the jet; physics that is not modeled directly in most RMHD codes. This talk presents a study of the differences in the polarized emission emanating from leptonic and hadronic jets using large scale 3D relativistic Particle-in-Cell (PIC) simulations. These PIC simulations are able to model the dynamic and radiative differences in the jet plasma at a kinetic level.