Radio Galaxies (3) ...
We believe that generally radio lobes, and the more compact RF emitting regions of core-halo
radio galaxies, are produced by jets ejected in back-to-back directions
from a powerful engine lying at the core of the
galaxy. These jets form strong radio emitting regions when they are stopped by the surrounding
cold, neutral matter. In essence, the jets inflate pockets of hot gas that emit large amounts
of radio frequency radiation. These pockets correspond to extended
radio lobes that we observe when
powerful
jets are oriented more at right angles to our sight, and to more compact core-halo sources
if the jets are oriented more along the line-of-sight or are less powerful. The following figure
illustrates this idea.
The hot gas
eventually leaks out of these pockets, but it is constantly replenished as long as the central
engine of the AGN is running. As we have suggested, and will discuss in detail shortly, this
central AGN engine is likely to be a spinning, supermassive black hole.
