A double-lobed radio galaxy gets its name from the fact that it emits radio energy from two regions, one on each side of the galaxy. Although galaxies are enormous, the radio lobes of these AGN are generally much larger than the galaxy in which they originate. Many are as large as 60 kpc in diameter, which is twice the size of the Milky Way Galaxy.
Radio lobes produce extremely intense radiation called synchrotron radiation .
Synchrotron radiation is produced when electrons which are moving at nearly the speed of light spiral through a magnetic field. Generally, the radio lobes are thought to be caused by the interaction of a jet of high energy gas and the surrounding medium. As these jets stream out of the nucleus of the galaxy, they must move through the intergalactic medium. Because the jet is moving with a much higher speed than the medium, shocks form at the ends of the jet. The radio lobe includes the hot spot and the material in the wake of the jet.