X-ray spectral variations in supernova remnants
Abstract
Supernovae (SNe) and their remnants are critical tools for understanding such areas of astrophysics as galaxy evolution, star formation, cosmology, and cosmic ray origins. In this dissertation, we explore how X-ray spectral variations provide a way to draw out clues from supernova remnants (SNRs) that may improve their use as astrophysical tools. In our first studies of two remnants, we investigate absorption, abundance; and emission type variations. For N63A, we discover an intervening absorbing cloud currently being engulfed by the remnant. Our study of 0509--67.5 reveals the need for a component of non-thermal emission at the rim of the SNR, indicating possible sites of cosmic ray acceleration. The abundances we derive for this SNR put constraints on allowed SN Ia explosion models. While these studies are successful at gleaning important information about the remnants, the techniques we use to identify the spectral variations are somewhat ad hoc. Thus, we explore the use of a more versatile, relatively unbiased technique, a principal components analysis (PCA). We pioneer its application to SNRs through Tycho's SNR. PCA picks out previously known variations, but allows for a more quantitative assessment of them. This feature allows us to separate cleanly line-dominated from featureless regions in Tycho. We argue that the resulting morphology is evidence for the acceleration of cosmic ray ions at the forward shock. A completely new variation is revealed, as well, whose interpretation points to differences in the oxygen and sulfur abundances in what was thought to be a fairly homogeneous remnant. Lastly, we apply PCA to Cas A, the remnant of a core-collapse SN. PCA unveils regions with unusual spectra, which may be used to explore the SNR evolution and SN explosion asymmetries.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 2006
- Bibcode:
- 2006PhDT........13W
- Keywords:
-
- Supernova remnants;
- X-ray spectra