Quasar Death

Supermassive black holes pass through several 'ages' - birth, rapid
growth at high redshift, moderate growth as quasars, merger growth,
and slow growth as radio galaxies and Seyferts, and finally a
turn-off. Downsizing of active black holes toward the present measn
that turned off quasarsa  remain quiescent, a kind of "quasar death".
Most of  this life cycle is very poorly known, with only the quasar
phase well studied. I will describe our new studies, based on both the
COSMOS and the SDSS DR5 quasar samples, which shed light on this
quasar death phase, as well as adding new complexity to the quasar
and merger growth phases. These studies include a careful examination
of the Mass-Luminosity plane for quasars, and the nature of 'intrinsically
red' quasars based on joint optical and X-ray observations.