Are spine-sheath polarization structures in the jets of active galactic nuclei associated with helical magnetic fields?

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dc.contributor.author Gabuzda, Denise
dc.contributor.author Reichstein, A. R.
dc.contributor.author O'Neill, E. L.
dc.date.accessioned 2017-11-07T09:38:53Z
dc.date.available 2017-11-07T09:38:53Z
dc.date.issued 2014
dc.identifier.citation Gabuzda, D. C., Reichstein, A. R. and O'Neill, E. L. (2014) 'Are spine–sheath polarization structures in the jets of active galactic nuclei associated with helical magnetic fields?', Monthly Notices of the Royal Astronomical Society, 444(1), pp. 172-184. doi: 10.1093/mnras/stu1381 en
dc.identifier.volume 444
dc.identifier.issued 1
dc.identifier.startpage 172
dc.identifier.endpage 184
dc.identifier.issn 0035-8711
dc.identifier.issn 1365-2966
dc.identifier.uri http://hdl.handle.net/10468/4954
dc.identifier.doi 10.1093/mnras/stu1381
dc.description.abstract One possible origin for polarization structures across jets of active galactic nuclei (AGNs) with a central 'spine' of orthogonal magnetic field and a 'sheath' of longitudinal magnetic field along one or both edges of the jet is the presence of a helical jet magnetic field. Simultaneous Very Long Baseline Array (VLBA) polarization observations of AGN displaying partial or full spine-sheath polarization structures were obtained at 4.6, 5.0, 7.9, 8.9, 12.9 and 15.4 GHz, in order to search for additional evidence for helical jet magnetic fields, such as transverse Faraday rotation gradients (due to the systematic change in the line-of-sight magnetic-field component across the jet). Results for eight sources displaying monotonic transverse Faraday rotation gradients with significances >= 3 sigma are presented here. Reversals in the directions of the transverse RM gradients with distance from the core or with time are detected in three of these AGNs. These can be interpreted as evidence for a nested helical magnetic field structure, with different directions for the azimuthal field component in the inner and outer regions of helical field. The results presented here support the idea that many spine-sheath polarization structures reflect the presence of helical magnetic fields being carried by these jets. en
dc.description.sponsorship National Science Foundation (AST-0607523) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Oxford University Press en
dc.relation.uri https://academic.oup.com/mnras/article/444/1/172/1010641/Are-spinesheath-polarization-structures-in-the
dc.rights © 2014, the Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society en
dc.subject Magnetic fields en
dc.subject Polarization en
dc.subject Galaxies en
dc.subject Active en
dc.subject Jets en
dc.title Are spine-sheath polarization structures in the jets of active galactic nuclei associated with helical magnetic fields? en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother Denise Gabuzda, Physics, University College Cork, Cork, Ireland. +353-21-490-3000 Email: d.gabuzda@ucc.ie en
dc.internal.availability Full text available en
dc.description.version Published Version en
dc.contributor.funder National Science Foundation
dc.description.status Peer reviewed en
dc.identifier.journaltitle Monthly Notices of the Royal Astronomical Society en
dc.internal.IRISemailaddress d.gabuzda@ucc.ie en


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