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dc.contributor.authorAggarwal, Poornima
dc.contributor.authorTaylor, David K.
dc.contributor.authorSmith, Charles W.
dc.contributor.authorJoyce, Colin J.
dc.contributor.authorFisher, Meghan K.
dc.contributor.authorIsenberg, Philip A.
dc.contributor.authorVasquez, Bernard J.
dc.contributor.authorSchwadron, Nathan A.
dc.contributor.authorCannon, Bradford E.
dc.contributor.authorRichardson, John D.
dc.date.accessioned2016-10-25T16:14:44Z
dc.date.available2016-10-25T16:14:44Z
dc.date.issued2016-05
dc.date.submitted2016-01
dc.identifier.issn1538-4357
dc.identifier.issn0004-637X
dc.identifier.urihttp://hdl.handle.net/1721.1/104969
dc.description.abstractWe report observations by the Voyager 1 and 2 spacecraft of low-frequency magnetic waves excited by newborn interstellar pickup ions H⁺ and He⁺ during 1978–1979 when the spacecraft were in the range from 2 to 6.3 au. The waves have the expected association with the cyclotron frequency of the source ions, are left-hand polarized in the spacecraft frame, and have minimum variance directions that are quasi-parallel to the local mean magnetic field. There is one exception to this in that one wave event that is excited by pickup H+ is right-hand polarized in the spacecraft frame, but similar exceptions have been reported by Cannon et al. and remain unexplained. We apply the theory of Lee & Ip that predicts the energy spectrum of the waves and then compare growth rates with turbulent cascade rates under the assumption that turbulence acts to destroy the enhanced wave activity and transport the associated energy to smaller scales where dissipation heats the background plasma. As with Cannon et al., we find that the ability to observe the waves depends on the ambient turbulence being weak when compared with growth rates, thereby allowing sustained wave growth. This analysis implies that the coupled processes of pitch-angle scattering and wave generation are continuously associated with newly ionized pickup ions, despite the fact that the waves themselves may not be directly observable. When waves are not observed, but wave excitation can be argued to be present, the wave energy is simply absorbed by the turbulence at a rate that prevents significant accumulation. In this way, the kinetic process of wave excitation by scattering of newborn ions continues to heat the plasma without producing observable wave energy. These findings support theoretical models that invoke efficient scattering of new pickup ions, leading to turbulent driving in the outer solar wind and in the IBEX ribbon beyond the heliopause.en_US
dc.description.sponsorshipUniversity of New Hampshire (Caltech subcontract 44A1085631)en_US
dc.description.sponsorshipUnited States. National Aeronautics and Space Administration (grant NNX13AF97G)en_US
dc.description.sponsorshipUnited States. National Aeronautics and Space Administration (grant NNX11AJ37G)en_US
dc.description.sponsorshipNational Science Foundation (U.S.) (grant AGS0962506)en_US
dc.description.sponsorshipNational Science Foundation (U.S.) (grant AGS1357893)en_US
dc.language.isoen_US
dc.publisherIOP Publishingen_US
dc.relation.isversionofhttp://dx.doi.org/10.3847/0004-637X/822/2/94en_US
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.en_US
dc.sourceAmerican Astronomical Societyen_US
dc.titleVOYAGER OBSERVATIONS OF MAGNETIC WAVES DUE TO NEWBORN INTERSTELLAR PICKUP IONS: 2–6 auen_US
dc.typeArticleen_US
dc.identifier.citationAggarwal, Poornima, David K. Taylor, Charles W. Smith, Colin J. Joyce, Meghan K. Fisher, Philip A. Isenberg, Bernard J. Vasquez, Nathan A. Schwadron, Bradford E. Cannon, and John D. Richardson. “VOYAGEROBSERVATIONS OF MAGNETIC WAVES DUE TO NEWBORN INTERSTELLAR PICKUP IONS: 2–6 Au.” The Astrophysical Journal vol. 822, no. 2, 94, May 2016, pp. 1-13. © 2016. The American Astronomical Society.en_US
dc.contributor.departmentMIT Kavli Institute for Astrophysics and Space Researchen_US
dc.contributor.mitauthorRichardson, John D
dc.relation.journalAstrophysical Journalen_US
dc.eprint.versionFinal published versionen_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dspace.orderedauthorsAggarwal, Poornima; Taylor, David K.; Smith, Charles W.; Joyce, Colin J.; Fisher, Meghan K.; Isenberg, Philip A.; Vasquez, Bernard J.; Schwadron, Nathan A.; Cannon, Bradford E.; Richardson, John D.en_US
dspace.embargo.termsNen_US
mit.licensePUBLISHER_POLICYen_US
mit.metadata.statusComplete


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