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

Authors :
John Wardle
Source :
Galaxies, Vol 6, Iss 1, p 5 (2018)
Publication Year :
2018
Publisher :
MDPI AG, 2018.

Abstract

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.

Details

Language :
English
ISSN :
20754434
Volume :
6
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Galaxies
Publication Type :
Academic Journal
Accession number :
edsdoj.fcf858add0343ceae4a3192458fb2a4
Document Type :
article
Full Text :
https://doi.org/10.3390/galaxies6010005