The spectropolarimetric test of the quasar emission mechanism

The spectral energy distribution of ordinary quiescent quasars is dominated by the ''big blue bump'' continuum component in the optical/UV region. This has been modeled as a viscous dissipative thin disk, though fundamental problems with that model are known. Here we test the dramatic polarization predictions for one such model. Pure scattering atmospheres are ruled out by existing data. However, the models of Laor, Netzer, & Piran have significant absorption opacity. They indicate that the optical light and that shortward of the Lyman edge may have low polarization but that the 1000-2000 Angstrom region may be significantly polarized. The position angle should be perpendicular to the radio axis where available. We do not see the predicted behavior. The polarization data also constrain reprocessing models for the disk.