VLBA Multi-frequency Polarimetric imaging of Radio-loud Broad Absorption Line Quasars

TL;DR

This study used multi-frequency VLBA polarimetric imaging to analyze four BAL quasars, revealing some as blazar-like with aligned jets and others as young radio sources, providing insights into their jet orientations and evolution.

Contribution

First multi-frequency polarimetric VLBA imaging of BAL quasars, distinguishing between blazar-like and young radio source characteristics.

Findings

Three quasars show blazar-like one-sided jets with polarized cores.

One quasar exhibits features of a young radio source with steep spectrum components.

Jet viewing angles are constrained to less than 66 degrees.

Abstract

We conducted the first multi-frequency polarimetric imaging of four broad absorption line (BAL) quasars using Very Long Baseline Array at milli-arcsecond resolutions to investigate the inclination of the non-thermal jet and test the hypothesis that radio sources in BAL quasars are still young. Among these four sources, J0928+446, J1018+0530, and J1405+4056 show one-sided structures in parsec scales, and polarized emission detected in the core. These characteristics are consistent with those of blazars. We set constraints on viewing angles to $<$66 deg for these jets, in the framework of a Doppler beaming effect. J1159+0112 exhibits an unpolarized gigahertz peaked spectrum component and several discrete blobs with steep spectra on both sides of the central component across $\sim$1 kpc. These properties are consistent with those of young radio sources. We discuss the structures of jets and AGN wind.