Observations and Simulations of Relativistic Jets

The recent improvement in VLBI arrays is providing information of the emission and magnetic field structure of relativistic jets, both extragalactic and galactic (microquasars), with unprecedented spatial and temporal resolution. These observations are revealing the importance of the hydrodynamical processes that govern the jet evolution, which can be studied by the recently developed time-dependent relativistic hydrodynamical models. Computation of the non-thermal emission from these hydrodynamical models, and its comparison with actual sources, is proving as one of the most powerful tools in the understanding of the physical processes taking place in these jets. This paper reviews some of the recent observational results, as well as the numerical models used to interpret them.