Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Superfluid hydrodynamics in neutron stars(Montana State University - Bozeman, College of Letters & Science, 1991) Mendell, Gregory AllenItem A study in quantum hydrodynamics(Montana State University - Bozeman, College of Letters & Science, 1960) Zook, Herbert A.Item Hydrodynamic analysis of coupled plasmons(Montana State University - Bozeman, College of Letters & Science, 1970) Burdick, David LeoItem Combining hydrodynamic modeling with nonthermal test particle tracking to improve flare simulations(Montana State University - Bozeman, College of Letters & Science, 2009) Winter, Henry deGraffenried, III; Chairperson, Graduate Committee: Petrus MartensSolar flares remain a subject of intense study in the solar physics community. These huge releases of energy on the Sun have direct consequences for humans on Earth and in space. The processes that impart tremendous amounts of energy are not well understood. In order to test theoretical models of flare formation and evolution, state of the art, numerical codes must be created that can accurately simulate the wide range of electromagnetic radiation emitted by flares. A direct comparison of simulated radiation to increasingly detailed observations will allow scientists to test the validity of theoretical models. To accomplish this task, numerical codes were developed that can simulate both the thermal and nonthermal components of a flaring plasma, their interactions, and their emissions. The HYLOOP code combines a hydrodynamic equation solver with a nonthermal particle tracking code in order to simulate the thermal and nonthermal aspects of a flare. A solar flare was simulated using this new code with a static atmosphere and with a dynamic atmosphere, to illustrate the importance of considering hydrodynamic effects on nonthermal beam evolution. The importance of density gradients in the evolution of nonthermal electron beams was investigated by studying their effects in isolation. The importance of the initial pitch-angle cosine distribution to flare dynamics was investigated. Emission in XRT filters were calculated and analyzed to see if there were soft X-ray signatures that could give clues to the nonthermal particle distributions. Finally the HXR source motions that appeared in the simulations were compared to real observations of this phenomena.Item Relativistic accretion flows onto supermassive black holes : shock formation and iron fluorescent emission lines in active galactic nuclei(Montana State University - Bozeman, College of Letters & Science, 2005) Fukumura, Keigo; Chairperson, Graduate Committee: Sachiko TsurutaOne of the exciting discoveries from the recent X-ray spectroscopic studies of active galactic nuclei (AGNs) is the so called βrelativistically-broadened iron fluorescent emission lineγ often detected in the hard X-ray spectra. It is generally believed to originate from the inner part of the accretion disk surrounding a supermassive black hole (BH) at the center. Although we have begun to obtain some physical insight regarding such emission lines supported by theoretical models (e.g., disk-corona model), exactly how and where the observed fluorescence may take place is still disputable. Here, an X-ray data with XMM-Newton Observatory of a typical narrow-line Seyfert 1 galaxy, NGC 4051, is analyzed based on a partial covering model to consistently explain the observed time-resolved temporal/spectral variations. This model implies that the intrinsic emission varies significantly in the presence of the covering cloud. We often detect a hard X-ray continuum originating from a hot region close to the central engines of AGNs. As a promising X-ray source candidate, relativistic hydrodynamic (HD) shocks are investigated systematically and then extended to the magnetohydrodynamic (MHD) shocks, given the widely accepted suggestion that the presence of the magnetic fields could play an important role in the accreting flows. I show that both HD and MHD shocks can form in the vicinity of the BH, perhaps responsible for creating such a hightemperature region where hard X-rays are produced. Particularly in the MHD shocked plasma, the hydro/magneto-dominated states are found. Considering the effect of such magnetic fields in the accretion disk, I calculate nonstandard iron fluorescent line profiles in the presence of spiral density waves and find multiple sharp sub-peak structures in extremely skewed line profiles, which will be detectable with upcoming X-ray satellites such as Astro-E2 XRS for testing the model. This dissertation is the result of my own work and also includes some work done in collaboration. Parts of this dissertation have been either already published in or submitted to the Astrophysical Journal and presented at conferences, while some are still in progress.