POLARIZATION CLUES TO THE STRUCTURE OF BROAD ABSORPTION LINE QUASI-STELLAR OBJECTS

摘要

Spectropolarimetry of two broad absorption line (BAL) QSOs, PHL 5200 and H1413+117, is presented. In both cases we find that the continuum polarization rises gently to the blue, and the emission lines are polarized less than, but at the same position angle as, the continuum. This implies that scattering is the polarization mechanism. In H1413+117 we also find a dramatic rise in polarization through the absorption troughs, which suggests that the scattered light is less absorbed than the direct light. We are led to a picture in which the scatterers lie near the equatorial plane of the QSO and arc physically associated with either the broad emission line region (BELR) or broad absorption line region (BALR). The direct light and the emission lines appear to be attenuated by passage through the BALR and/or scattering region. The scattered light passes through a region with less absorption, both in the continuum and in the BAL troughs.