Clues to Outflows: Polarization of IRAS-Selected QSOs

Broad-band polarimetry and spectropolarimetry of a complete sample of 18 luminous AGNs (Lbol ≥ 10 L⊙), selected in an orientation-independent way by warm infrared flux, shows that an orientation – dust-covering Unified Scheme like that successfully explored for the lower luminosity Seyfert galaxies applies to the luminous QSOs. Broad emission lines and continuum seen in polarized (scattered) light show that hyperluminous infrared galaxies contain buried QSO nuclei and are therefore the ‘missing’ QSO 2s – the high-luminosity analogs of Seyfert 2 galaxies like NGC 1068. Most of the QSOs show significant polarization and reddening. Three are ‘classical’ low-ionization BAL QSOs, and several others have narrower, blueshifted, low-ionization absorption. These properties are to be compared with those of the UV-optically selected QSOs, of which only ∼1% show low-ionization BALs, and only the BAL QSOs show significant polarization. Outflows are therefore much more common than previously suspected. 1. The Relevance of Polarized IRAS AGNs to Mass Ejection from