Computational studies of the transverse structure of AGN jets

dc.check.embargoformatNot applicableen
dc.check.infoNo embargo requireden
dc.check.opt-outNot applicableen
dc.check.reasonNo embargo requireden
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dc.contributor.advisorGabuzda, Deniseen
dc.contributor.authorMurphy, Eoin Gerard
dc.contributor.funderIrish Research Council for Science Engineering and Technologyen
dc.date.accessioned2014-09-29T13:49:36Z
dc.date.available2014-09-29T13:49:36Z
dc.date.issued2014
dc.date.submitted2014
dc.description.abstractBoth the emission properties and the evolution of the radio jets of Active Galactic Nuclei are dependent on the magnetic (B) fields that thread them. A number of observations of AGN jets suggest that the B fields they carry have a significant helical component, at least on parsec scales. This thesis uses a model, first proposed by Laing and then developed by Papageorgiou, to explore how well the observed properties of AGN jets can be reproduced by assuming a helical B field with three parameters; pitch angle, viewing angle and degree of entanglement. This model has been applied to multifrequency Very Long Baseline Interferometry (VLBI) observations of the AGN jets of Markarian 501 and M87, making it possible to derive values for the helical pitch angle, the viewing angle and the degree of entanglement for these jets. Faraday rotation measurements are another important tool for investigating the B fields of AGN jets. A helical B field component should result in a systematic gradient in the observed Faraday rotation across the jet. Real observed radio images have finite resolution; typical beam sizes for cm-wavelength VLBI observations are often comparable to or larger than the intrinsic jet widths, raising questions about how well resolved a jet must be in the transverse direction in order to reliably detect transverse Faraday-rotation structure. This thesis presents results of Monte Carlo simulations of Faraday rotation images designed to directly investigate this question, together with a detailed investigation into the probabilities of observing spurious Faraday Rotation gradients as a result of random noise and finite resolution. These simulations clearly demonstrate the possibility of detecting transverse Faraday-rotation structures even when the intrinsic jet widths are appreciably smaller than the beam width.en
dc.description.sponsorshipIrish Research Council for Science Engineering and Technology (EMBARK Initiative)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationMurphy, E. G. 2014. Computational studies of the transverse structure of AGN jets. PhD Thesis, University College Cork.en
dc.identifier.urihttps://hdl.handle.net/10468/1671
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2014, Eoin G. Murphyen
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectAGNen
dc.subjectInterferometryen
dc.subjectFaraday rotationen
dc.subjectRadio astronomyen
dc.subjectHelical magnetic fieldsen
dc.thesis.opt-outfalse
dc.titleComputational studies of the transverse structure of AGN jetsen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Science)en
ucc.workflow.supervisord.gabuzda@ucc.ie
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