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   52083
   Thermal X-ray emission from extragalactic Supernovae, with age less
   than ~ 50 years, is most likely due to the interaction of the expanding
   Supernova debris with circumstellar medium. Since radio frequency
   radiation also originates in this interaction region, we propose a
   search for x-rays among known strong radio Supernovae. As the
   environment and progenitor evolution of type II and type Ib Supernovae
   are different, the nature of the X-ray emission can reflect these
   differences and we propose both types of Supernovae. These studies are
   expected to address key questions regarding progenitor evolution
   leading to Supernovae, nature of the circumstellar medium and the
   Supernova ejecta.
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