We have used the optical polarization properties of BL Lacertae objects to gain insights into the range and physical causes of their extreme and spectacular observed properties. This dissertation consists of three parts. In Part I we provide an introduction to BL Lacs and other active galactic nuclei. In Part II we present the result of an extensive monitoring program of the optical polarization of x-ray selected BL Lacs (XSBLs). In Part III we present the results of the most extensive optical polarization survey so far undertaken. Our study of the optical polarization properties of XSBLs confirms that the BL Lac candidates found in x-ray surveys like the Einstein Extended Medium Sensitivity Survey meet the requirements for membership in the class of BL Lacs. In addition to having featureless optical spectra, the majority of the XSBLs are also variable in their flux output and have intrinsic and variable polarized emission. Although x-ray selected BL Lac candidates have proven to be BL Lacs, the characteristics of their optical polarized emission are different from those of the classical radio selected BL Lacs. The XSBLs have lower maximum percent polarizations, a lower duty cycle, smaller variations in flux, and a greater tendency to have preferred angles of polarization than radio selected BL Lacs (RSBLs). We discuss the consequences of these differences and their consistency with the "beaming" model first proposed by Blandford and Rees (1978). Our optical polarization survey is the most extensive survey of its kind ever undertaken. The survey is complete to a B magnitude of 20 and covers 560 square degrees. Our sensitivity to polarized objects is a function of survey field. We did not find any confirmed BL Lacs or highly polarized quasars, but we are able to constrain the surface density of the various populations of polarized objects. For example we are able to rule out at the 90.0% confidence level the presence of a population of radio quiet BL Lacs or highly polarized quasars (with optical flux and polarization properties similar to radio selected BL Lacs) that would have a cumulative surface density of 0.03 per square degree down to a B magnitude of 20.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 282-294). Available also in a digital version from Dissertation Abstracts.

The investigation of the host galaxies of BL Lac objects (BL Lacs) is a promising new field made practical in recent years by advances in detector technology and improved telescope siting. By better understanding the nature of these host galaxies we can test the standard beaming and lensing models for BL Lacs. This thesis describes the techniques that we have developed for studying the host galaxies of BL Lac objects, and presents the results of a survey of BL Lac host galaxies that we have undertaken with the 4.2m William Herschel Telescope. This survey successfully resolved many new host galaxies, determined the morphology of three BL Lac host galaxies for the first time, and confirmed the morphology of an additional three objects. One BL Lac object, PKS1413+135, displayed a number of surprising properties, and was consequently studied in greater detail at multiple wavelengths. These observations are also presented in this thesis. We conclude with a description of Monte-Carlo simulations that we have undertaken in order to better determine the uncertainty in the results from our survey, and to assess the promise of future telescope/instrumentation combinations for host galaxy imaging.

Thesis (Ph. D.) - University of Adelaide, 2003. / Bibliography: leaves 191-202.

Thesis (Ph.D.) - Boston University, 2010.

No description available.

Bibliography: leaves 191-202. 1. Introduction -- 2. Instrumentation and calibration -- 3. A radio monitoring program for southern blazars -- 4. Analysis of long-term blazar radio variability -- 5. Probing microarcsecond-scale structure using interstellar scintillation -- 6. The rapid scintillator, PKS 1257-326 -- 7. Conclusions and scope for further work.

Thesis (Ph. D.)--School of Physics, Faculty of Science, University of Sydney, 2004. / Bibliography: p. 123-129.

Thesis (Ph. D.)--University of Sydney, 2004. / Title from title screen (viewed 14 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Degree awarded 2004; thesis submitted 2003. Includes bibliographical references. Also available in print form.

Thesis (Ph. D.)--University of Adelaide, 2003. / Title from title screen. Description based on contents viewed Apr. 21, 2005. Includes bibliographical references.