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oai:www.ideals.illinois.edu:2142/34587 2023-07-11 col_2142_14807 col_2142_5131 com_2142_14806 com_2142_8903 com_2142_5130

Kemball, Athol J. Kemball, Athol J. Crutcher, Richard M. Looney, Leslie W. Sutton, Edmund C. Mitra, Modhurita 2012-09-18T21:26:54Z 2012-09-18T21:26:54Z 2014-09-18T10:01:02Z 2012-08 2012-09-18T21:26:54Z 2012-08 The goals of this thesis were to study the observational radio-polarimetric properties of gravitational lens systems. Such studies can constrain lensed source properties, propagation effects in the intervening lensing galaxies, and the general-relativistic invariance of polarization under lensing. We performed high dynamic-range VLBI imaging polarimetry of the gravitational lens system B0218+357 at 43 GHz, and further VLBI observations of this system in the frequency range 8 GHz - 43 GHz. Further analysis included a low-frequency VLA study of the gravitational lens system B0218+357 over the frequency range 330 MHz - 5 GHz. We also studied the VLA polarization morphology of a sample of gravitational lens systems over the frequency range 1.5 MHz - 43 GHz, and used contemporary algorithms to estimate rotation measure values of the lens sample. In addition, we proposed a framework for evaluating the performance of fringe-fit methods in the low SNR regime using bootstrap resampling. Our 43 GHz maps of B0218+357 provide the highest-resolution constraints on the detailed polarization morphology of the background source to date, confirm parity reversal in polarization structure predicted by gravitational lensing theory, and verify the invariance of polarization properties under gravitational lensing. We present absolute rotation measures, lensing galaxy magnetic field estimates, and the fractional linear polarization distribution for our lensing population sample. We propose a new explanation for the earlier puzzling radial polarization structure in the Einstein ring in B0218+357. In closing, we verify that bootstrap resampling is an effective framework for assessing the performance of fringe-fitting estimators as needed in millimeter-wavelength VLBI. Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-07-10T15:17:11Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Mitra_Modhurita.pdf: 7363631 bytes, checksum: b91c6d1eae940c1d76b4ccc3b9988188 (MD5) Made available in DSpace on 2012-09-18T21:26:54Z (GMT). No. of bitstreams: 2 Mitra_Modhurita.pdf: 7398052 bytes, checksum: c2cce5a3be6f63196eef8f77fb4fdabf (MD5) license.txt: 4063 bytes, checksum: 8ce95649a6c2c9f07d3e16d509607e85 (MD5) Restriction data tranferred 2014-07-01T11:35:55-05:00 Original Data Group with Access Administrator Release Date: 2014-09-18 16:27:16 UTC Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system Item marked as restricted to the 'Administrator' Group (id=1) by Seth Robbins (srobbins@illinois.edu) on 2012-09-18T21:27:37Z Item is restricted until 2014-09-18T21:27:16Z Limited Restriction Lifted for Item 34861 on 2014-09-18T10:01:02Z. http://hdl.handle.net/2142/34587 en Copyright 2012 Modhurita Mitra Radio astronomy gravitational lensing interferometry polarization Faraday rotation Radio-polarimetric observations of gravitational lenses Astronomy 1430 Astronomy 0333 University of Illinois at Urbana-Champaign Dissertation Ph.D. PHD:Astronomy -UIUC 10KS0333PHD