The role of AGN in the migration of early-type galaxies from the blue cloud to the red sequence

Abstract

We present a general picture of the ongoing formation and evolution of early-type galaxies via a specific evolutionary sequence starting in the blue cloud and ending in the low-mass end of the red sequence. This evolutionary sequence includes a Seyfert AGN phase in the green valley, but this phase occurs too late after the shutdown of star formation to be responsible for it. Thus, the bulk of black hole accretion in low-redshift early-type galaxies occurs in post-starburst objects, and not concurrent with star formation. On the other hand, a low-luminosity AGN phase switching on at an earlier stage when some star formation activity remains may be responsible for destroying the molecular gas reservoir fueling star formation.Comment: 4 pages, 2 figures. To appear in proceedings of "The Monster's Fiery Breath", Madison, Wisconsin, 1-5 June 2009, Ed. Sebastian Heinz & Eric Wilcot