Transition from red to blue quasars (annotated)

An artist’s impression of the transition from red to blue quasars. Red and blue quasars are related within an evolutionary sequence that connects dust-obscured star formation with quasar activity through gas inflow via merging galaxies and outflows from the quasar. With this model the rare red quasar population represents a brief transitional phase between the starburst and the blue quasar phase during which winds and/or jets drive away the obscuring dust, revealing an unobscured blue quasar, and ultimately shutting down the star formation to form a dormant early-type galaxy.