Host Galaxies of Obscured Quasars: Infant Starbursts Caught in Action

摘要

Supermassive black holes (SMBHs) in the centers of massive galaxies are thought to predom-inantly grow in brief Eddington-rate quasar phases accompanied by starbursts, but on-going starbursts in luminous quasars are difficult to observe. Buried under the natural coronagraph, obscured quasars offer a unique window for direct, robust host-galaxy spectroscopy otherwise virtually inaccessible for luminous quasars. Our pilot study at z-0.5 (Liu et al. 2009) revealed a substantial contribution from very young stellar populations with ages less than — 100 Myr in all of the observed host galaxy spectra. More dramatically, in three out of the nine SDSS quasars observed, we have witnessed strong infant starbursts with ages of 5 Myr, clocked by the telltale Wolf-Rayet emission features.