Relativistic Jets and Blazars
| Professors: Cui, Giannios, Lister, Lyutikov Relativistic jets are focussed outflows originating close to supermassive black holes at the center of some quasars and radio galaxies. There is still some uncertainty as to their basic composition, but we do know that they act as conduits for transporting energy over intergalactic distances. We also are convinced that the bulk of the radiation we detect from the jets is produced by relativistic electrons. The jet flows have been seen to approach velocities very close to the speed of light, making them subject to exotic effects associated with special relativity, such as time dilation, apparent superluminal motion, and light aberration. Blazars are a subclass of quasars and radio galaxies, and their extreme brightness and variability are explained by that one of their jets is pointed almost exactly towards the Earth. Whenever an emitting volume is moving close to the speed of light, its radiated energy is concentrated into the forward direction, producing a narrow cone of emission. This relativistic beaming effect explains a blazar's extreme brightness and why only the approaching jet is usually detected. |
 This frame from a simulation by Jonathan McKinney (KIPAC), shows a black hole pulling in nearby matter (yellow) and spraying energy back out into the universe in a jet (blue and red) that is held together by magnetic field lines (green). |