What the X-Ray Emission from Young Supernovae Can Tell Us About Their Progenitors

We discuss constraints that the X-ray emission from supernovae can place on their progenitor stars. Since almost all X-ray supernovae arise from massive stars, we concentrate on implications for massive stars. These stars lose mass throughout their lifetime in the form of stellar winds. X-ray emission can be used to gauge the wind properties, especially the mass-loss rates, via various techniques. The abundance of various elements formed by nucleosynthesis within the stars, and released in the stellar explosion, can be estimated from X-ray spectra. In many cases, a combination of X-ray light curves and spectra can allow us to extricate the structure and morphology of the surrounding medium formed by pre-supernova mass loss into which the SN shock is expanding.