X-Ray Emission from the Type I[CLC]c[/CLC] Supernova 1994I Observed with [ITAL]Chandra[/ITAL]

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 M~1×10-5 Msolar 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).