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Extreme Scattering Events: An Observational Summary

  • T. Joseph W. Lazio
  • Alan L. Fey
  • R. A. Gaume
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Abstract

We review observational constraints on the structures responsible for extreme scatteringevents, focussing on a series of observations of the quasar PKS 1741-038. VLA observations wereconducted to search for changes in the rotation measure and HI absorption during the ESE, whileVLBI observations sought ESE-induced changes in the source’s image. No RM changes were foundimplying B∥ < 12 mG, and no HI opacity changes were found implying (HI) < 6.4 x 1017 cm-2.No multiple imaging was observed, but the diameter of the source increased by 0.7 mas, contrary towhat is predicted by simple refractive lens modeling of ESEs. We summarize what these limits implyabout the structure responsible for this ESE.

Keywords

Column Density Multiple Imaging Faraday Rotation Observational Constraint Angular Diameter 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media Dordrecht 2001

Authors and Affiliations

  • T. Joseph W. Lazio
    • 1
  • Alan L. Fey
    • 2
  • R. A. Gaume
    • 2
  1. 1.Naval Research LaboratoryUSA
  2. 2.US Naval ObservatoryUSA

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