Evidence for toroidal B-field components in AGN jets on kiloparsec scales

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dc.contributor.author Knuettel, Sebastian
dc.contributor.author Gabuzda, Denise
dc.contributor.author O'Sullivan, Shane
dc.date.accessioned 2017-12-08T13:33:48Z
dc.date.available 2017-12-08T13:33:48Z
dc.date.issued 2017-10-04
dc.identifier.citation Knuettel, S., Gabuzda, D. and O’Sullivan, S. (2017) 'Evidence for toroidal B-field components in AGN jets on kiloparsec scales', Galaxies, 5(4), 61 (6pp). doi: 10.3390/galaxies5040061 en
dc.identifier.volume 5
dc.identifier.issued 4
dc.identifier.startpage 1
dc.identifier.endpage 6
dc.identifier.issn 2075-4434
dc.identifier.uri http://hdl.handle.net/10468/5154
dc.identifier.doi 10.3390/galaxies5040061
dc.description.abstract Though helical magnetic fields are generally believed to arise when the jets of Active Galactic Nuclei (AGN) are launched, it is still unclear what role they play (and if they survive) to the largest jet scales. A helical or toroidal B-field may contribute substantially to the collimation of the jet. This B-field structure can be detected in images of the Faraday rotation measure (RM)—a measure of the change in polarisation angle of an electromagnetic wave as it passes through a magneto-ionic medium. The Faraday rotation measure is directly proportional to the line-of-sight magnetic field; therefore a monotonic gradient in the RM transverse to the jet indicates similar behaviour of the line-of-sight B-field component. This type of analysis has mostly been done on parsec scales using VLBI observations at centimetre wavelengths, while relatively few studies have probed decaparsec to kiloparsec scales. The detection of RM gradients with significances of 3σ or more on such large scales can demonstrate the presence of a toroidal field component, which may be associated with a helical field that has persisted to these distances from the centre of the AGN. We present the results of new Faraday rotation analyses for 2 AGN on kiloparsec scales based on multiwavelength VLA observations, with robust transverse RM gradients detected in both. Furthermore, the direction of the inferred toroidal B-fields on the sky supports previous results indicating a predominance of outward currents in the jets on kiloparsec scales. en
dc.description.sponsorship Irish Research Council (Government of Ireland Postgraduate Scholarship) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher MDPI en
dc.relation.uri http://www.mdpi.com/2075-4434/5/4/61
dc.rights © 2017, the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). en
dc.rights.uri https://creativecommons.org/licenses/by/4.0/
dc.subject Active galactic nuclei en
dc.subject Magnetic fields en
dc.subject Radio interferometry en
dc.title Evidence for toroidal B-field components in AGN jets on kiloparsec scales en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother Sebastian Knuettel, Physics, University College Cork, Cork, Ireland. +353-21-490-3000 Email: s.knuettel@mars.ucc.ie en
dc.internal.availability Full text available en
dc.description.version Published Version en
dc.contributor.funder Irish Research Council
dc.description.status Peer reviewed en
dc.identifier.journaltitle Galaxies en
dc.internal.IRISemailaddress s.knuettel@mars.ucc.ie en
dc.identifier.articleid 61


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© 2017, the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Except where otherwise noted, this item's license is described as © 2017, the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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