Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 288-296). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Chicago, Department of Astronomy and Astrophysics, August 2003. / Includes bibliographical references. Also available on the Internet.

published_or_final_version / Physics / Master / Master of Philosophy

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Observations from a broad range of astrophysical scales have forced us to the realization that the well understood matter comprising the stars and galaxies we see around us accounts for only a small fraction of the total mass of the Universe. An amount roughly five times larger exist in the form of dark matter about which we have virtually no direct evidence apart from its large scale gravitational effects. It is also known that the largest contribution to the energy density of the universe is the dark energy, a negative pressure form of energy which will not be dealt with here. I will present a candidate for the dark matter which is based completely in known physics and which presents several possible observational signatures. In this model the dark matter is composed of dense nuggets of baryonic matter and antimatter in a colour superconducting state. If these object are sufficiently massive their low number density will make them effectively dark in the sense that collisions with visible matter become infrequent. This work presents the basics of dark matter as a colour superconductor and then uses the physical properties of the quark nuggets to extract observational consequences.

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The synchrotron emissivity distribution of the Milky Way Galaxy has been modelled from the 408 MHz allsky survey of Haslam et al.(1982) after separation of its thermal component with the help of IRAS 60 micron emission(Broadbent et al 1989). We have refined the spiral arm pattern in the inner part of the Galaxy by including a bar at the Galactic centre and an updated the Galactic distance scale and obtained fitted free parameters. At 408 MHz, there is very little absorption in the interstellar medium and the line of sight distribution of synchrotron emissivity was inferred mainly from its presumed relationship to the other tracers of spiral structure via these fitted free parameters. At lower frequencies, the absorption of synchrotron emission due to thermal electrons becomes significant and can give direct information of the nonthermal distribution along the line of sight. We have modelled the distribution of thermal electrons according to our synchrotron arm model and an alternative model based on pulsar dispersion measures using the Galactic rotation curve and the surveys of the distribution of Hl66a emission We have then used our synchrotron model applied at lower frequencies including the absorption to compare with the surveys of Dwarakanath et al.(l990) at 34.5 MHz and Jones and Finlay(l974) at 29.9 MHz. The result confirms that the absorption model of the synchrotron emissivity in the Galactic plane is broadly correct and illustrates the potentials of the absorption technique. However we were not able to distinguish the two models of ionised hydrogen spiral structure. To do this, recombination line surveys with improved frequency resolution are required. Using a new value of the cosmic ray gradient in the Galaxy from diffuse gamma-ray emission we obtain the separate variation of magnetic field and cosmic ray electron density. We give the global properties of the thermal and nonthermal emission that our model implies.

Thesis (PhD) - Swinburne University of Technology, 2007. / Submitted for the degree of Doctor of Philosophy, Swinburne University of Technology - 2007. Typescript. "May 2007". Bibliography: p. 225-237.