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Paper: Diffraction from 2d Lenses in the ISM
Volume: 365, SINS — Small Ionized and Neutral Structures in the Diffuse Interstellar Medium
Page: 275
Authors: Stinebring, D.; Matters, J.; Hemberger, D.
Abstract: One explanation for extreme scattering events (quasar flux variations with ringing and an extended flux minimum lasting for weeks) is refraction by lens-like structures in the ISM. Prompted by this and intriguing features in pulsar scintillation arcs, we have used an e-m wave propagation code to explore the flux time signature expected for a 2d lens with a Gaussian column density profile.This builds on the work of Clegg, Fey, and Lazio (1998; CFL), but considers 2d rather than 1d lens structures and simulates the light curves with a wave optics approach. We find results that are consistent with CFL in many ways, but demonstrate a richer interference structure at entry and egress from the lens. Also, we do not see evidence for an inner caustic in these 2d simulations. It is possible that the inner caustic is an artifact of the 1d model that CFL analyzed.
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