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R. Petre (NASA/GSFC), U. Hwang (NASA/GSFC and UMD), S.S. Holt (NASA/GSFC), E.V. Gotthelf (Columbia), E.M. Schlegel (SAO/CXC), N. Schulz (MIT/CXC)
Using data from the first light Chandra observation of the SNR Cas A, we investigate global X-ray spectral variations across the remnant by comparing spectra of the X-ray bright ring with those of the lower surface brightness regions, both exterior and interior to the bright ring. While both sets of spectra are dominated by line emission, those from low surface brightness regions are qualitatively different, with significantly lower line equivalent widths for all elements. These differences arise from a combination of abundance variations and plasma conditions. It is likely that emission from the bright ring arises primarily from ejecta heated by the reverse shock, while the low surface brightness emission arises primarily from circumstellar material heated by the forward shock. Thus the Chandra data allow the isolation of the spectrum of the outer shock from the emission of the bright shell for the first time. Supporting radio results are presented in an accompanying poster.
The author(s) of this abstract have provided an email address for comments about the abstract: rob@hatrack.gsfc.nasa.go