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Title: The jets in radio galaxies
Author: Hardcastle, M. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1997
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I present high-resolution, high-sensitivity images of four FRI radio galaxies and seventeen FRII radio galaxies, made with the aim of detecting and imaging jets and counterjets. For the FRIs, I show images of the detailed total intensity and polarisation structure in the jets and counterjets and in the sources as a whole. I argue that models in which the jets are initially relativistic but decelerate are a good fit to the overall behaviour of the objects, but that some recent models of the polarisation structure are ruled out by the observations. The radio-optical spectrum of the jet in one object is discussed in some detail. For the seventeen FRIIs (part of a complete sample of 21 objects) I detect new jets or possible jets in a number of objects; there are jets or probable jets in 76% of the sample as a whole. The properties of the hot spots of the objects and their implications for models of radio sources are discussed. I use my observations, together with data from previous work, to define an unbiased sample of 50 radio galaxies, and measure quantities of interest from the maps available to me. Trends in this sample are discussed and compared with those seen in samples of other classes of object. Using Monte Carlo simulation, I show that the prominences and sidednesses of jets in the sample are consistent with relativistic beaming models, and constrain the velocities required and the efficiency of a typical beam.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available