2023MNRAS.519.2773B

We present polarization images of nine radio-loud (RL) quasars from the VLA B-array at 6 GHz. These quasars belong to the Palomar-Green (PG) 'blazar' sample comprising 16 RL quasars and eight BL Lac objects. Extensive polarization is detected in the cores, jets, and lobes of all the quasars, with cores primarily displaying magnetic (B-) fields transverse to, and jets displaying fields aligned with the jet direction. Hotspots display either transverse B-fields signifying B-field compression at terminal shocks or more complex structures. The fractional polarization in the cores ranges from 1 per cent to 10 per cent and jets/lobes from 10 per cent to 40 per cent. Several of the quasars show distorted or hybrid FRI/FRII radio morphologies with indications of restarted active galactic nucleus activity. We attribute this to the optical/UV selection criteria of the PG sample that remains unbiased at radio frequencies. The in-band spectral indices of the radio cores are relatively flat, while they are steep in the hotspots. This is consistent with the polarization structures where the hotspots appear to be locations of jet bends or bow-shocks. We present global properties for the entire PG 'blazar' sample. We find that jet powers correlate with accretion rates for the quasars; higher accretion rates result in more powerful radio jets. A correlation between the radio core fractional polarization and the 150 MHz total radio luminosity for the nine quasars studied here may imply that more organized B-fields at the jet bases lead to higher core fractional polarization and to more powerful radio jets.