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J.S. Warren, J.P. Hughes, C. Badenes (Rutgers University)
We present results from a Principal Component Analysis (PCA) of Tycho's supernova remnant (SNR). PCA is a statistical technique we implemented to characterize X-ray spectra extracted from distinct spatial regions across the entire image of the remnant. We used the PCA to determine the location of the contact discontinuity (CD) in Tycho, which marks the boundary between shocked ejecta and shocked interstellar material, and found an azimuthal-angle-averaged radius of 241". For the average radius of the outer blast wave (BW) we found 251". Taking account of projection effects, the ratio of BW:CD is 1:0.93, which is inconsistent with adiabatic hydrodynamic models of SNR evolution. The BW:CD ratio can be explained if cosmic ray acceleration of ions is occurring at the forward shock. Such a scenario is further supported by evidence from the morphology and spectral nature of the BW emission for the acceleration of cosmic ray electrons. We also present PCA results regarding the ranges in Si and Fe composition in Tycho, and a newly uncovered spectral variation in the form of a low energy excess that has not been previously noted.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.