How do quasars and active galaxies differ from normal galaxies?

Question

Hazel Asher · Accepted Answer

Quasars and active galaxies have material falling into a supermassive black hole.

Supermassive black holes are found at the centers of most galaxies, and most of them are not very full of material falling into them. A wealth of gas and dust surrounds the central black hole in young galaxies and galaxies that have collided with one another; as the material falls into the black hole, it forms an accretion disk. A quasar, or active galaxy, is created when a large amount of material falls into the accretion disk and becomes superheated due to friction and gravitational effects. This process releases a great deal of energy in the form of electromagnetic radiation. When the galaxy's supply of material falling into the accretion disk runs out, it turns into a typical, dormant galaxy.

Luke Allen · Answer

undefined High luminosities, driven by accretion onto supermassive black holes at their centers, are characteristics of quasars and active galaxies that set them apart from normal galaxies. These extreme features include strong radio emissions and rapid variability.