The spatial, spectral and polarization properties of solar flare X-ray sources

Jeffrey, Natasha Louise Scarlet (2014) The spatial, spectral and polarization properties of solar flare X-ray sources. PhD thesis, University of Glasgow.

Abstract

X-rays are a valuable diagnostic tool for the study of high energy accelerated electrons. Bremsstrahlung X-rays produced by, and directly related to, high energy electrons accelerated during a flare, provide a powerful diagnostic tool for determining both the properties of the accelerated electron distribution, and of the flaring coronal and chromospheric plasmas. This thesis is specifically concerned with the study of spatial, spectral and polarization properties of solar flare X-ray sources via both modelling and X-ray observations using the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Firstly, a new model is presented, accounting for finite temperature, pitch angle scattering and initial pitch angle injection. This is developed to accurately infer the properties of the acceleration region from the observations of dense coronal X-ray sources. Moreover, examining how the spatial properties of dense coronal X-ray sources change in time, interesting trends in length, width, position, number density and thermal pressure are found and the possible causes for such changes are discussed. Further analysis of data in combination with the modelling of X-ray transport in the photosphere, allows changes in X-ray source positions and sizes due to the X-ray albedo effect to be deduced. Finally, it is shown, for the first time, how the presence of a photospheric X-ray albedo component produces a spatially resolvable polarization pattern across a hard X-ray (HXR) source. It is demonstrated how changes in the degree and direction of polarization across a single HXR source can be used to determine the anisotropy of the radiating electron distribution.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Solar physics, solar flare, corona, chromosphere, X-rays, RHESSI
• Subjects: Q Science > QB Astronomy; Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Kontar, Dr. Eduard P.
• Date of Award: 2014
• Depositing User: Dr Natasha L. S. Jeffrey
• Unique ID: glathesis:2014-5310
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Aug 2014 12:29
• Last Modified: 11 Sep 2014 08:58
• URI: https://theses.gla.ac.uk/id/eprint/5310