Spectropolarimetry of low redshift Quasars: origin of the polarization
  and implications for black hole mass estimates
  We present the results of high signal-to-noise ratio VLT spectropolarimetry
of a representative sample of 25 bright type 1 AGN at z<0.37, of which nine are
radio-loud. The sample covers uniformly the 5100 A optical luminosity at
$L_{5100}\sim 10^{44}-10^{46}$ erg s$^{-1}$, and H$\alpha$ width at FWHM$\sim
1000-10,000$~ km/s. We derive the continuum and the H$\alpha$ polarization
amplitude, polarization angle, and angle swing across the line, together with
the radio properties. We find the following: 1. The broad line region (BLR) and
continuum polarization are both produced by a single scattering medium. 2. The
scattering medium is equatorial, and at right angle to the system axis. 3. The
scattering medium is located at or just outside the BLR. The continuum
polarization and the H$\alpha$ polarization angle swing, can both serve as an
inclination indicator. The observed line width is found to be affected by
inclination, which can lead to an underestimate of the black hole mass by a
factor of $\sim 5$ for a close-to face-on view. The line width measured in the
polarized flux overcomes the inclination bias, and provides a close-to
equatorial view of the BLR in all AGN, which allows to reduce the inclination
bias in the BLR based black hole mass estimates.
