Active galaxy types, illustration. Active galaxies are those with an active galactic nucleus (AGN), driven by a central supermassive black hole. Types of AGNs include radio-quiet and radio-loud AGNs. Other classifications include low-ionization nuclear emission-line regions (LINERs), Seyfert galaxies, quasars (quasi-stellar objects), and blazars. AGNs emit a range of non-stellar radiation, including radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray radiation. The features commonly seen in an AGN are the opaque torus, an accretion disc around the central supermassive black hole, and relativistic jets (blue), which are beams of ionised matter accelerated close to the speed of light. These beams are seen head-on at upper left.