A galaxy that is an unusually powerful emitter of radio waves. The output of a radio galaxy can be up to 1038 watts, a million times greater than a normal galaxy such as our own. Radio galaxies have a compact radio nucleus coincident with the core of the visible parent galaxy, a pair of opposed jets emerging from the nucleus, and a pair of lobes (1) far outside the visible confines of the galaxy. The galaxy is almost always a giant elliptical, which may be the result of the collision and merger of two or more smaller galaxies. The source of the radio galaxy's energy is believed to be a massive black hole in the galactic nucleus from which the jets emerge, delivering energy to the lobes. Notable radio galaxies include Centaurus A, Cygnus A, and Virgo A.
Subjects: Astronomy and Astrophysics.