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dc.contributor.authorGrillo Csaszar, Gianfranco
dc.date.accessioned2018-10-23T13:22:03Z
dc.date.available2018-10-23T13:22:03Z
dc.date.issued2018-05-30
dc.identifier.otherGrilloCsaszar_cornell_0058O_10307
dc.identifier.otherhttp://dissertations.umi.com/cornell:10307
dc.identifier.otherbibid: 10489442
dc.identifier.urihttps://hdl.handle.net/1813/59357
dc.description.abstractPlasma lensing events can have significant observational consequences, including flux modulations and perturbations in pulse arrival times. In this paper we develop and apply a formalism based on an extension of geometric optics that can be used to describe the effects of two dimensional plasma lenses of arbitrary shape. We apply insights from catastrophe theory and the study of uniform asymptotic expansions of integrals to describe the lensing amplification close to fold caustics and in shadow regions, and explore the effects of image appearance and disappearance at caustics in the TOA perturbations due to lensing. We find that the enhanced geometric optics approach successfully reproduces the predictions from wave optics, and that it can be efficiently used to simulate multifrequency TOA residuals during lensing events. Lensing will introduce perturbations in these residuals that will manifest as an increased spreading in the data points at lower frequencies, and will deviate from the expected dispersive $\nu^{-2}$ scaling most significantly when including observations at low frequencies, $\nu<0.7$ GHz.
dc.language.isoen_US
dc.subjectAstronomy
dc.subjectISM
dc.subjectpulsars
dc.subjectPlasma lensing
dc.subjectOptics
dc.subjectAstrophysics
dc.subjectscintillation
dc.titleWave Asymptotics and their Application to Astrophysical Plasma Lensing
dc.typedissertation or thesis
thesis.degree.disciplineApplied Physics
thesis.degree.grantorCornell University
thesis.degree.levelMaster of Science
thesis.degree.nameM.S., Applied Physics
dc.contributor.chairLovelace, Richard V. E.
dc.contributor.committeeMemberCordes, James Martin
dcterms.licensehttps://hdl.handle.net/1813/59810
dc.identifier.doihttps://doi.org/10.7298/X4T151XG


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