Scalar Fields in Astrophysics

[摘要] This thesis is about the possible consequences of the existence of scalar particles on astrophysical objects, particularly neutron stars. The existence of such particles is hypothesized by certain developments in elementary particle theory. These particles are assumed to be lights having masses less than, or of approximately one electron volt. The stipulation that these particles are light is in no way discriminatory; it just so happens that over astrophysical distances lighter particles have far greater influence because of their greater range, i.e. their Compton wavelength, and so are more interesting in this context. The introduction of this work will, after giving a brief historical summary of each subject, show how scalar fields arise in various theoretical contexts within the disciplines of particle physics and cosmology. It will also show how highly interlinked these disciplines are, and how developments in each drive and influence the other. Also included in the introduction will be a review of neutron stars and their properties and a summary of the methods of nuclear theory. The first chapter consists of the construction of an explicit model of static neutron star and scalar field configurations. The properties of these configurations are discussed at length and then used to give bounds on the coupling of this hypothetical scalar field to ordinary matter. Certain technical difficulties arising from the presence of the scalar field are also discussed. The second chapter consists of a study of the radial oscillations of the static configurations which were found in the preceding chapter. The equations of motion for the oscillations of the neutron star and scalar field are derived, after which the stability of the configurations is discussed with particular reference to the possibility of monopole scalar radiation. Lastly, an approximate calculation is made of the relaxation time of radial oscillations for a star which is radiating scalar waves. The last chapter contains a simple model of gravitational collapse with a scalar field, constructed in the manner of the Oppenheimer-Snyder model. After integration of the Einstein equations for the interior, the problem of matching to an appropriate exterior is considered. It is found that, contrary to naive expectation, matching is greatly complicated by the presence of a scalar field; both technical and conceptual problems are found to arise. Finally, the necessary conditions and procedures for construction of more general exterior solutions, which this problem seems to require, are given and discussed.

[发布机构] University:University of Glasgow

[关键词] Astrophysics, Theoretical physics