Magnetic field strength and spectral distribution of six parsec-scale active galactic nuclei jets

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dc.contributor.authorO'Sullivan, S. P.
dc.contributor.authorGabuzda, Denise
dc.contributor.funderIrish Research Council for Science, Engineering and Technology
dc.date.accessioned2017-11-07T09:38:55Z
dc.date.available2017-11-07T09:38:55Z
dc.date.issued2009
dc.description.abstractWe use observations of six 'blazars' with the Very Long Baseline Array (VLBA), at eight frequencies (4.6, 5.1, 7.9, 8.9, 12.9, 15.4, 22.2 and 43.1 GHz), to investigate the frequency-dependent position of their VLBI cores ('core-shift') and their overall jet spectral distribution. By cross-correlating the optically thin jet emission, we are able to accurately align the multifrequency images of three of the jets (1418+546, 2007+777, 2200+420), whose core-shifts and spectra we find consistent with the equipartition regime of the Blandford & Konigl conical jet model, where the position of the radio core from the base of the jet follows r(core)(nu) proportional to nu-1. For the jet of 0954+658, we align the higher frequency images using our lower frequency measurements assuming equipartition in the radio core from 4.6-43 GHz. The jet emission of the other two sources in our sample (1156+295, 1749+096) is too sparse for our alignment technique to work. Using our measured core-shifts, we calculate equipartition magnetic field strengths of the order of 10s to 100s of mG in the radio cores of these four AGN from 4.6-43 GHz. Extrapolating our results back to the accretion disc and black hole jet-launching distances, we find magnetic field strengths consistent with those expected from theoretical models of magnetically powered jets.en
dc.description.statusPeer revieweden
dc.description.versionPublished Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationO'Sullivan, S. P. and Gabuzda, D. C. (2009) 'Magnetic field strength and spectral distribution of six parsec-scale active galactic nuclei jets', Monthly Notices of the Royal Astronomical Society, 400(1), pp. 26-42. doi: 10.1111/j.1365-2966.2009.15428.xen
dc.identifier.doi10.1111/j.1365-2966.2009.15428.x
dc.identifier.endpage42
dc.identifier.issn0035-8711
dc.identifier.issued1
dc.identifier.journaltitleMonthly Notices of the Royal Astronomical Societyen
dc.identifier.startpage26
dc.identifier.urihttps://hdl.handle.net/10468/4969
dc.identifier.volume400
dc.language.isoenen
dc.publisherOxford University Pressen
dc.relation.urihttps://academic.oup.com/mnras/article-lookup/doi/10.1111/j.1365-2966.2009.15428.x
dc.rights© 2009, the Authors. Journal compilation © 2009, RASen
dc.subjectGalaxiesen
dc.subjectJetsen
dc.subjectMagnetic fieldsen
dc.subjectRadio continuumen
dc.titleMagnetic field strength and spectral distribution of six parsec-scale active galactic nuclei jetsen
dc.typeArticle (peer-reviewed)en
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