Parsec-scale Faraday rotation and polarization of 20 active galactic nuclei jets

2017/01/05 by E. V. Kravchenko, Е. В. Кравченко, Y. Y. Kovalev +1 · 2 citations
Physics and Astronomy · #Active galactic nucleus #Astrophysics #Astrophysics and Cosmic Phenomena #Faraday cage #Faraday effect #Galaxy #Gamma-ray bursts and supernovae #Linear polarization #Magnetic field #Optics #Physics #Polarimetry #Polarization (electrochemistry) #Quasar #Radio Astronomy Observations and Technology #Scattering #Very Long Baseline Array #Wavelength #astro-ph.HE

paper · pdf · doi:10.1093/mnras/stx021

published as MNRAS 467 (2017) 83 · 19 pages, 8 figures, 9 tables; published by MNRAS; full versions of the table 3 and figures 2, 5 and 8 are available in the journal version of the paper

openalex publication_date 2017/01/05 · arxiv created 2018/03/09 · arxiv updated 2018/03/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

We perform polarimetry analysis of 20 active galactic nuclei jets using the very long baseline array at 1.4, 1.6, 2.2, 2.4, 4.6, 5.0, 8.1, 8.4 and 15.4 GHz. The study allowed us to investigate linearly polarized properties of the jets at parsec scales: distribution of the Faraday rotation measure (RM) and fractional polarization along the jets, Faraday effects and structure of Faraday-corrected polarization images. Wavelength dependence of the fractional polarization and polarization angle is consistent with external Faraday rotation, while some sources show internal rotation. The RM changes along the jets, systematically increasing its value towards synchrotron self-absorbed cores at shorter wavelengths. The highest core RM reaches 16 900 rad m−2 in the source rest frame for the quasar 0952+179, suggesting the presence of highly magnetized, dense media in these regions. The typical RM of transparent jet regions has values of an order of a hundred rad m−2. Significant transverse RM gradients are observed in seven sources. The magnetic field in the Faraday screen has no preferred orientation, and is observed to be random or regular from source to source. Half of the sources show evidence for the helical magnetic fields in their rotating magneto-ionic media. At the same time jets themselves contain large-scale, ordered magnetic fields and tend to align its direction with the jet flow. The observed variety of polarized signatures can be explained by a model of spine–sheath jet structure.

Citations

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Cited by

• Analytical Solution of Magnetically Dominated Astrophysical Jets and Winds: Jet Launching, Acceleration, and Collimation
• Polarimetric Properties of Event Horizon Telescope Targets from ALMA