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M. F. Theiling, M. D. Leising (Clemson University)
Current theory holds that radioactive 44Ti (/tau1/2=60y) produced in supernovae is the source for the abundance of 44Ca in our Galaxy. The decay chain of 44Ti-->44Sc-->44Ca produces several detectable gamma-ray lines, most notably the 1157 keV nuclear de-excitation of 44Ca. However, the electron capture by which 44Ti becomes 44Sc leaves a gap in the K-shell and can lead to subsequent photon emission. This emission should be detectable as an X-ray line at 4.1 keV in young supernova remnants (SNR). Thus 44Ti as a product of supernova nucleosynthesis may directly measured through detection of these X-ray lines.
CasA, a realtively young galactic Type II SNR bright in the X-ray band is a logical place to search for 44Ti. Gamma-ray lines emitted by the daughter nucleus 44Ca has already been detected in CasA using the Compton Gamma-Ray Observatory (Iyudin, et.al. 1994). Given the wealth of X-ray observations of the CasA SNR and these detections, we have begun a search for this X-ray line. Employing public data from both NASA's Chandra X-ray Observatory and the ESA's X-ray Multiple Mirror Mission (XMM), we have generated X-ray spectra and utilized best-fit models to determine line strengths. Preliminary results return a 2\sigma upper limit to the 4.1 keV line flux of ~3.0*10-5. This non-detection is not in conflict with the aforementioned gamma-ray observations.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.