Analysing the Transverse Structure of the Relativistic Jets of AGN

Abstract

This paper describes a method of fitting total intensity and polarization profiles in VLBI images of astrophysical jets to profiles predicted by a theoretical model. As an example, the method is used to fit profiles of the jet in the Active Galactic Nucleus Mrk501 with profiles predicted by a model in which a cylindrical jet of synchrotron plasma is threaded by a magnetic field with helical and disordered components. This fitting yields model Stokes Q profiles that agree with the observed profiles to within the 1-2 σuncertainties; the I model and observed profiles are overall not in such good agreement, with the model I profiles being generally more symmetrical than the observed profiles. Consistent fitting results are obtained for profiles derived from 6cm VLBI images at two distances from the core, and also for profiles obtained for different wavelengths at a single location in the VLBI jet. The most striking success of the model is its ability to reproduce the spine-sheath polarization structure observed across the jet. Using the derived viewing angle in the jet rest frame, δ' approximately 83 degrees, together with a superluminal speed reported in the literature, βapparent = 3.3, yields a solution for the viewing angle and velocity of the jet in the observer's frame δdegrees and βapproximately 0.96. Although these results for Mrk501 must be considered tentative, the combined analysis of polarization profiles and apparent component speeds holds promise as a means of further elucidating the magnetic field structures and other parameters of parsec-scale AGN jets.

Accepted for publication by MNRAS

References in corpus (5)

• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VIII. Faraday rotation in parsec-scale AGN jets
• The jet of Markarian 501 from millions of Schwarzschild radii down to a few hundreds
• A relativistic model of the radio jets in 3C 296
• Multifrequency VLA observations of the FR I radio galaxy 3C 31: morphology, spectrum and magnetic field
• Significant Limb-Brightening in the Inner Parsec of Markarian 501

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• Relevance of jet magnetic field structure for blazar axionlike particle searches
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• 18-22 cm VLBA Faraday rotation studies of six AGN jets
• Imaging VLBI polarimetry data from Active Galactic Nuclei using the Maximum Entropy Method
• Survey of Non-thermal Electron around Supermassive Black Holes through Polarization Flips
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• Depolarization and Faraday effects in AGN Jets
• Multi-scale Radio and X-ray Structure of the High-redshift Quasar PMN J0909+0354
• Jet Archaeology and Forecasting: Image Variability and Magnetic Field Configuration
• The observed polarization direction depending on geometrical and kinematic parameters of relativistic jets
• Peculiar Behavior of Optical Polarization in Blazar 1ES 1959+650: Role of Jet Magnetic Field and Geometry
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