Relativistic Jets in Active Galactic Nuclei

Relativistic jets are a well-established feature of the influence of supermassive black holes in active galactic nuclei. There are two candidate processes for the launching of a jet from the vicinity of a black hole – a centrifugally driven outflow from the surface of the accretion disk or an outflow that relies on the physics of processes occurring in the ergosphere. The emission from jets spans the entire electromagnetic spectrum – form radio waves through to the highest energy gamma rays. Emission in gamma rays and the rapid variability of this emission pose interesting questions concerning the velocities of jets with some estimates of the Lorentz factor as high as 50 within a 100 gravitational radii of the black hole.