Misalignment of the Jet and the Normal to the Dusty Torus in the Broad Absorption Line QSO FIRST\,J155633.8+351758

TL;DR

This study uses VLBA radio observations and polarization data to investigate the geometry of a radio-loud broad absorption line quasar, revealing a tilted dusty torus and aligned outflows, challenging simple symmetric models.

Contribution

It provides the first detailed geometric analysis of a radio-loud BALQSO using multi-wavelength data, highlighting a tilted dusty torus and aligned outflows.

Findings

The radio jet is partially resolved with a secondary component at PA ≈ 35°.

The jet is viewed within 14.3° of the line of sight.

The dusty torus is tilted relative to the accretion disk normal.

Abstract

We performed VLBA observations of the Broad Absorption Line Quasar FIRST\,J155633.8+351758, "the first radio loud BALQSO". Our observations at 15.3 GHz partially resolved a secondary component at positional angle (PA) $\approx 35^{\circ}$. We combine this determination of the radio jet projection on the sky plane, with the constraint that the jet is viewed within $14.3^{\circ}$ of the line of sight (as implied by the high variability brightness temperature) and with the position angle (PA) of the optical/UV continuum polarization in order to study the quasar geometry. Within the context of the standard model, the data indicates a "dusty torus" (scattering surface) with a symmetry axis tilted relative to the accretion disk normal and a polar broad absorption line outflow aligned with the accretion disk normal. We compare this geometry to that indicated by the higher resolution radio data, brightness temperature and optical/UV continuum polarization PA of a similar high optical polarization BALQSO, Mrk\,231. A qualitatively similar geometry is found in these two polar BALQSOs; the continuum polarization is determined primarily by the tilt of the dusty torus.