Spectropolarimetry of NGC 3783 and Mrk 509: evidence for powerful nuclear winds in Seyfert 1 galaxies

Abstract

We present results from high signal-to-noise optical spectropolarimetric observations of the Seyfert 1 galaxies NGC3783 and Mrk 509 in the 3500-7000 angstrom range. We find complex structure in the polarized emission for both objects. In particular, Position Angle (PA) changes across the Balmer lines show a distinctive 'M'-shaped profile that had not been observed in this detail before, but could represent a common trait in Seyfert 1 galaxies. In fact, while this shape is observed in all Balmer lines in NGC3783, Mrk 509 transitions into a 'M'-shaped PA profile for higher transitions lines. We have modelled the observed profiles using the STOKES radiative transfer code and assuming that the scattering region is co-spatial with the BLR and outflowing. The results give compelling new evidence for the presence of nuclear winds in these two Seyfert 1 galaxies.