A Polarimetric Study of 9 PG Quasars with the VLA
arXiv:2212.07061 · doi:10.1093/mnras/stac3691
Abstract
We present polarization images of 9 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 8 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 1-10% and jets/lobes from 10-40%. Several of the quasars show distorted or hybrid FRI/FRII radio morphologies with indications of restarted AGN 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 9 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.
24 pages, 21 figures, MNRAS accepted
References in corpus (13)
- Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
- Revisiting the Fanaroff-Riley dichotomy and radio-galaxy morphology with the LOFAR Two-Metre Sky Survey (LoTSS)
- The Origin of the Intrinsic Scatter in the Relation Between Black Hole Mass and Bulge Luminosity for Nearby Active Galaxies
- Hydrodynamical Backflow in X-shaped Radio Galaxy PKS 2014-55
- LOFAR imaging of Cygnus A -- Direct detection of a turnover in the hotspot radio spectra
- Accretion mode versus radio morphology in the LOFAR Deep Fields
- Identifying the subtle signatures of feedback from distant AGN using ALMA observations and the EAGLE hydrodynamical simulations
- Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies
- The debeamed luminosity, sychrotron peak frequency and black hole mass of BL Lac objects
- VLBI Observations of a sample of Palomar-Green quasars I: parsec-scale morphology
- The Quasar Feedback Survey: Revealing the Interplay of Jets, Winds & Emission Line Gas in Type 2 Quasars with Radio Polarization
- A VLA-GMRT Look at 11 Powerful FR II Quasars
- VLA Snapshot Continuum Survey of FRI Quasar Candidates Selected from the LOFAR Two-Metre Sky Survey (LoTSS)