To be used for astrophysical jets -- collimated, relativistic outflows often due to accretion onto compact objects.
The common feature is a highly energetic process launching particles along a rotation axis at relativistic speeds. The acceleration and collimation of jets can be influenced by pressure gradients in the ambient medium and strong electromagnetic fields. Their emission can be seen over a wide range of the electromagnetic spectrum. Relativistic jets not only provide a means of seeing effects of objects otherwise too faint to study, but they are also a natural laboratory for relativistic plasma physics.