New Insights into the Quasar Type1/Type2 Dichotomy from Correlations between Quasar Host Orientation and Polarization

TL;DR

This study reveals a significant correlation between polarization angles and host galaxy orientations in quasars, supporting an extended unification model involving scattering regions, with differences observed between type1 and type2 quasars.

Contribution

It provides new high-resolution measurements linking polarization and host galaxy orientation, extending the unification model to luminous quasars with a two-component scattering framework.

Findings

Significant correlation between polarization and host galaxy orientation.

Different correlation patterns for type1 and type2 quasars.

Supports a two-component scattering model in quasars.

Abstract

We investigate correlations between the direction of the optical linear polarization and the orientation of the host galaxy/extended emission for type1 and type2 radio-loud and radio-quiet quasars. We have used high resolution Hubble Space Telescope data and a deconvolution process to obtain a good determination of the host galaxy/extended emission (EE) position angle. With these new measurements and a compilation of data from the literature, we find a significant correlation, different for type1 and type2 objects, between the linear polarization position angle and the orientation of the EE, suggesting scattering by an extended UV/blue region in both types of objects. Our observations support the extension of the Unification Model to the higher luminosity AGNs like the quasars, assuming a two component scattering model.