Starburst galaxies -- AGN connection: Theoretical scenario

Abstract

Starburst galaxies are characterized by a very high central infrared luminosity of about 10/sup10/ - 10/sup12/ solar luminosity. This luminosity is attributed to a burst of formation of massive stars. The stellar radiation is absorbed by dust and re-radiated thermally in the infrared. Active Galactic Nuclei (AGN) are very energetic, non-thermal, compact nuclear sources believed to be powered by accretion of gas onto the central black hole. Both, starburst galaxies and AGN, are seen to occur preferentially in interacting field galaxies. A galaxy interaction causes gas infall from the disk, which may lead to the triggering of a central starburst which could then evolve to an AGN, or the gas infall may fuel a pre-existing central black hole. Starburst galaxies and AGN are both vast and extremely active areas of research today. Here, first the basic physical properties of starburst galaxies and AGN are highlighted. Next, some simple theoretical ideas regarding the evolution of starbursts to AGN are discussed. Implications of the starburst-AGN connection for the evolution of the quasar luminosity function are mentioned.