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Advanced Diagnostics for the Study of Linearly Polarized Emission. II. Application to Diffuse Interstellar Radio Synchrotron Emission

Herron, C. A.; Burkhart, Blakesley; Gaensler, B. M.; Lewis, Geraint Francis; McClure-Griffiths, Naomi; Bernardi, Gianni; Carretti, Ettore; Haverkorn, M.; Kesteven, M. J.; Poppi, Sergio; Staveley-Smith, Lister

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Diagnostics of polarized emission provide us with valuable information on the Galactic magnetic field and the state of turbulence in the interstellar medium, which cannot be obtained from synchrotron intensity alone. In Paper I, we derived polarization diagnostics that are rotationally and translationally invariant in the Q-U plane, similar to the polarization gradient. In this paper, we apply these diagnostics to simulations of ideal magnetohydrodynamic turbulence that have a range of sonic...[Show more]

dc.contributor.authorHerron, C. A.
dc.contributor.authorBurkhart, Blakesley
dc.contributor.authorGaensler, B. M.
dc.contributor.authorLewis, Geraint Francis
dc.contributor.authorMcClure-Griffiths, Naomi
dc.contributor.authorBernardi, Gianni
dc.contributor.authorCarretti, Ettore
dc.contributor.authorHaverkorn, M.
dc.contributor.authorKesteven, M. J.
dc.contributor.authorPoppi, Sergio
dc.contributor.authorStaveley-Smith, Lister
dc.date.accessioned2021-04-22T23:51:18Z
dc.identifier.issn0004-637X
dc.identifier.urihttp://hdl.handle.net/1885/230958
dc.description.abstractDiagnostics of polarized emission provide us with valuable information on the Galactic magnetic field and the state of turbulence in the interstellar medium, which cannot be obtained from synchrotron intensity alone. In Paper I, we derived polarization diagnostics that are rotationally and translationally invariant in the Q-U plane, similar to the polarization gradient. In this paper, we apply these diagnostics to simulations of ideal magnetohydrodynamic turbulence that have a range of sonic and Alfvénic Mach numbers. We generate synthetic images of Stokes Q and U for these simulations for the cases where the turbulence is illuminated from behind by uniform polarized emission and where the polarized emission originates from within the turbulent volume. From these simulated images, we calculate the polarization diagnostics derived in Paper I for different lines of sight relative to the mean magnetic field and for a range of frequencies. For all of our simulations, we find that the polarization gradient is very similar to the generalized polarization gradient and that both trace spatial variations in the magnetoionic medium for the case where emission originates within the turbulent volume, provided that the medium is not supersonic. We propose a method for distinguishing the cases of emission coming from behind or within a turbulent, Faraday rotating medium and a method to partly map the rotation measure of the observed region. We also speculate on statistics of these diagnostics that may allow us to constrain the physical properties of an observed turbulent region.
dc.description.sponsorshipC.A.H. acknowledges financial support received via an Australian Postgraduate Award and a Vice Chancellor’s Research Scholarship awarded by the University of Sydney. B.B. is supported by the NASA Einstein Postdoctoral Fellowship. B.M.G. acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) through grant RGPIN-2015-05948 and a Canada Research Chair. N.M.M.-G. acknowledges the support of the Australian Research Council through grant FT150100024. The Dunlap Institute for Astronomy and Astrophysics is funded through an endowment established by the David Dunlap family and the University of Toronto.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherIOP Publishing
dc.rights© 2018 The American Astronomical Society
dc.sourceThe Astrophysical Journal
dc.subjectISM: magnetic fields
dc.subjectISM: structure
dc.subjectmagnetohydrodynamics (MHD)
dc.subjectpolarization
dc.subjecttechniques: polarimetric
dc.titleAdvanced Diagnostics for the Study of Linearly Polarized Emission. II. Application to Diffuse Interstellar Radio Synchrotron Emission
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume855
dcterms.dateAccepted2018-02-13
dc.date.issued2018-03-05
local.identifier.absfor020104 - Galactic Astronomy
local.identifier.absfor020201 - Atomic and Molecular Physics
local.identifier.absfor030699 - Physical Chemistry not elsewhere classified
local.identifier.ariespublicationa383154xPUB9583
local.publisher.urlhttps://iopscience.iop.org/
local.type.statusPublished Version
local.contributor.affiliationHerron, C. A., University of Sydney
local.contributor.affiliationBurkhart, Blakesley, Harvard-Smithsonian Center for Astrophysics
local.contributor.affiliationGaensler, B. M., University of Sydney
local.contributor.affiliationLewis, Geraint Francis, University of Sydney
local.contributor.affiliationMcClure-Griffiths, Naomi, College of Science, ANU
local.contributor.affiliationBernardi, Gianni, Rhodes University
local.contributor.affiliationCarretti, Ettore, INAF
local.contributor.affiliationHaverkorn, M., Radboud University
local.contributor.affiliationKesteven, M. J., CSIRO, Australia Telescope National Facility
local.contributor.affiliationPoppi, Sergio, INAF Osservatorio Astronomico di Cagliari
local.contributor.affiliationStaveley-Smith, Lister, University of Western Australia
local.description.embargo2099-12-31
dc.relationhttp://purl.org/au-research/grants/arc/FT150100024
local.bibliographicCitation.issue29
local.bibliographicCitation.startpage1
local.bibliographicCitation.lastpage33
local.identifier.doi10.3847/1538-4357/aaafd0
dc.date.updated2020-11-23T11:31:46Z
local.identifier.scopusID2-s2.0-85044075752
CollectionsANU Research Publications

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