| This thesis presents the results of two studies involving collimated outflows in radio loud active galactic nuclei (AGN). The first study examines relativistic outflows from the cores of different classes of AGN, and estimates of bulk Lorentz factors and viewing angles. The second study deals with powerful extended radio galaxies, the relation between their lifetime and their luminosity in directed kinetic energy, or beam power, and the use of these sources for cosmology.; Compact radio sources are examined, and the kinematics of their outflows are determined. Two updated sets of Doppler factor estimates, one using the equipartition method and the other using the inverse Compton method, for 100 radio cores are discussed. Intrinsic brightness temperatures based on these Doppler factors are examined along with their relevance to the "inverse Compton catastrophe". Intrinsic luminosity densities and luminosities are presented, and the role of systematic errors is discussed. Outflow angles and bulk Lorentz factors are computed for 43 out of the 100 sources on the basis of proper motions compiled by Vermeulen & Cohen (1994). These estimates of outflow angles and bulk Lorentz factors are discussed along with their agreement with orientation unified models of AGN.; Powerful extended radio galaxies are examined, and the relation between the active lifetime and the beam power in these sources is investigated by comparing the redshift evolution of characteristic source size to the redshift evolution of the average lobe-lobe size. It is found that the data are described by a model in which the active lifetime of the source, {dollar}tsb{lcub}*{rcub},{dollar} is written as a power-law in the beam power, {dollar}Lsb{lcub}j{rcub}.{dollar} The exponent of the power law is estimated to be {dollar}betasimeq2.1pm0.6,{dollar} where {dollar}tsb{lcub}*{rcub}propto Lsbsp{lcub}j{rcub}{lcub}-beta/3{rcub},{dollar} which excludes {dollar}beta=0,{dollar} an Eddington-limited system. The same comparison of characteristic source sizes to the average lobe-lobe size can be used to constrain cosmological parameters. The data indicate a low value of {dollar}Omegasb{lcub}o{rcub},{dollar} which is about 2{dollar}sigma{dollar} away from an Einstein-de Sitter universe. |
