Studies in Gravitational Lensing and Numerical Hydrodynamics

• Main Author: Kochanek, Christopher Sharpe
• Format: Others
• Language: en
• Published: 1989
• Online Access: https://thesis.library.caltech.edu/1947/3/kochanek-cs_1989.pdf; Kochanek, Christopher Sharpe (1989) Studies in Gravitational Lensing and Numerical Hydrodynamics. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/fpn8-g713. https://resolver.caltech.edu/CaltechETD:etd-05222007-073908 <https://resolver.caltech.edu/CaltechETD:etd-05222007-073908>

<p>(1) The gravitational lensing cross sections for multiple imaging by elliptical galaxy potentials is examined. Lenses are found to divide into strong and marginal lenses. Three image systems form either <i>allied</i> geometries in which the two brightest images lie on the same side of the lens, or <i>opposed</i> geometries in which the two brightest images lie on opposite sides of the lens. Strong lenses are dominated by the three image opposed geometry at low amplifications and the five image geometry at high amplifications. Marginal lenses are dominated by the three image allied geometry.</p> <p>(2) The cross sections for multiple imaging are integrated over the expected distribution of lenses and sources. The sources are taken to be quasars with a standard number-magnitude relation. Approximately one in one thousand quasars will be multiply imaged. Bright lensed quasars are likely to have five images due to the effects of amplification bias.</p> <p>(3) Approximately one to ten percent of lens systems will involve more than one lensing galaxy either at the same or at a different redshift. The statistical properties of such "two screen" gravitational lenses are evaluated.</p> <p>(4) An inversion technique for resolved gravitational lenses is developed and applied to the radio ring image MG1131+0456. The technique works both for intensity and polarization maps. The velocity dispersion, position, ellipticity and position angle of the lens are tightly constrained - typically to within ten percent or two tenths of an arc second.</p> <p>(5) The propagation of a precessing hydrodynamic jet is studied using finite difference techniques in an axisymmetric system. The implications for the precessing jet in SS433 is examined. It is unlikely that the SS433 jet can be hydrodynamic in nature unless the kinetic luminosity is much lower than that required to form the lobes of the W50 remnant.</p> <p>(6) The tidal disruption of a star on a parabolic orbit past a supermassive black hole is examined using smooth particle hydrodynamics. The spectrum of specific energies for the debris is in close agreement with analytic expectations. Processes leading to the formation of an accretion disk are discussed.</p>