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The Variable Rotation Measure Distribution in 3C 273 on Parsec Scales

Physics Department, Brandeis University, Waltham, MA 02453, USA
Galaxies 2018, 6(1), 5; https://doi.org/10.3390/galaxies6010005
Received: 15 September 2017 / Revised: 17 December 2017 / Accepted: 18 December 2017 / Published: 5 January 2018
(This article belongs to the Special Issue Polarised Emission from Astrophysical Jets)
We briefly review how opacity affects the observed polarization in synchrotron emitting jets. We show some new multi-frequency observations of 3C 273 made with the VLBA in 1999–2000, which add significantly to the available rotation measure (RM) observations of this source. Our findings can be summarized as follows: (1) The transverse gradient in RM is amply confirmed. This implies a toroidal component to the magnetic field, which in turn requires a current of 1017–1018 A flowing down the jet. (2) The net magnetic field in the jet is longitudinal; however, whether or not the longitudinal component is vector-ordered is an open question. (3) The RM distribution is variable on timescales of months to years. We attribute this to the motion of superluminal components behind a turbulent Faraday screen that surrounds the jet. (4) Finally, we suggest that Faraday rotation measurements at higher resolution and higher frequencies, with the Event Horizon Telescope, may enable useful constraints to be placed on the accretion rate onto the central black hole. View Full-Text
Keywords: active galactic nuclei; 3C 273; polarization; opacity; Faraday rotation; magnetic fields active galactic nuclei; 3C 273; polarization; opacity; Faraday rotation; magnetic fields
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MDPI and ACS Style

Wardle, J. The Variable Rotation Measure Distribution in 3C 273 on Parsec Scales. Galaxies 2018, 6, 5. https://doi.org/10.3390/galaxies6010005

AMA Style

Wardle J. The Variable Rotation Measure Distribution in 3C 273 on Parsec Scales. Galaxies. 2018; 6(1):5. https://doi.org/10.3390/galaxies6010005

Chicago/Turabian Style

Wardle, John. 2018. "The Variable Rotation Measure Distribution in 3C 273 on Parsec Scales" Galaxies 6, no. 1: 5. https://doi.org/10.3390/galaxies6010005

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