Abstract
We present two high-resolution Chandra X-ray observations of supernova (SN) 1994I that show, for the first time, that the interaction of the blast wave from a Type Ic SN with its surrounding circumstellar material (CSM) can give rise to soft X-ray emission. Given a 0.3-2 keV band X-ray luminosity of LX ~ 1 × 1037 ergs s-1 between 6 and 7 years after the outburst of SN 1994I, and assuming the X-ray emission arises from the shock-heated CSM, we derive a pre-SN mass-loss rate of 
~ 1 × 10-5 M☉ yr-1(vw/10 km s-1). Combining the results with earlier ROSAT observations, we construct the X-ray light curve of SN 1994I. A best-fit X-ray rate of decline of LX ∝ t-s, with index s ~ 1 and a CSM density profile of ρcsm ∝ r-1.9±0.1, is inferred, consistent with what is expected for a constant mass-loss rate and a constant wind velocity profile for the SN progenitor (ρcsm ∝ r-2).
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