In order to better understand the nature of post-starburst quasars ( PSQs ) in the context of galaxy evolution , we compare their properties to those of post-starburst galaxies and quasars from appropriately selected samples possessing similar redshift ( z \sim 0.3 ) , luminosity ( M _ { r } \sim - 23 ) , and data quality .
We consider morphologies , spectral features , and derived physical properties of the stellar populations and central supermassive black hole .
PSQs themselves come in two types : the more luminous AGNs with more luminous post-starburst stellar populations hosted by elliptical galaxies , some which are clearly merger products , and the less luminous systems existing within relatively undisturbed spiral galaxies and possessing signs of a more extended period of star formation .
Post-starburst galaxies ( PSQs ) have elliptical and disturbed/post-merger morphologies similar to those of the more luminous PSQs , display similar spectral properties , but also can have younger stellar populations for a given starburst mass .
Quasars at similar redshifts and luminosities around the Seyfert/quasar transition possess similar AGN characteristics , in terms of black hole mass and accretion rate , compared with those of PSQs , but do not appear to be hosted by galaxies with significant post-starburst populations .
Recent studies of more luminous quasars find hosts consistent with those of our luminous PSQs , suggesting that these PSQs may be in transition between post-starburst galaxies and a more luminous quasar stage when the post-starburst stellar population remains dominant .
The lower luminosity PSQs appear to differ from lower luminosity quasars ( Seyfert galaxies ) in terms of more significant star formation in their past .