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Title: Astrophysical studies of the dynamics of diffuse matter in space
Author: Brand, Peter W. J. L.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1991
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The thesis deals with various astrophysical aspects of diffuse matter influenced by violent events. It divides into two parts, the first part dealing with studies of relativistic material (with particles moving at speeds close to that of light), and the second part with non-relativistic material. The first part investigates the properties of the radiation from blazars. These extreme forms of active galactic nucleus radiate powerfully from jets of relativistic electrons interacting with entrained magnetic fields. Our polarimetric studies have determined that the most violent events must be beamed towards us, and require energy released from the vicinity of a black hole; that the emission is most simply explained as due to electron acceleration by a magnetodynamic shock in a relatively quiescent jet of magnetized material; and that the very short timescales and high degree of polarization argue for extremely small-and therefore intense-emitting regions. The second part of the thesis details work on the diffuse material near star-forming regions, influenced by violent winds or intense UV fluxes. The work investigates in detail the properties of shocks in star-forming regions, establishing the strongly predictive hydrodynamic shock model; pointing out the difficulty of such models in the face of line profile data obtained by ourselves; and investigating analytically the possibility that such profiles may be the signature of magnetohydrodynamic shocks. Also described is the initial work using fluorescent emission from molecular hydrogen (and other data) to investigate the physics of photodissociation regions. These regions may be the main emission interface in external galaxies undergoing bursts of star-formation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (D.Sc.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available