A Chandra ACIS observation of the X-ray-luminous SN 1988Z

SN 1988Z is the most luminous X-ray-emitting supernova, initially detected in 1995 using the ROSAT HRI with a luminosity of similar to 8 x 10(40) ergs s(-1) (Fabian & Terlevich 1996). Its high luminosity was ascribed to expansion of the blast wave into an especially dense circumstellar medium. In this paper, we describe a recent observation of SN 1988Z using the ACIS detector on Chandra. We readily detect SN 1988Z, obtaining similar to 30 net counts, which corresponds to a 0.2-2.0 keV luminosity of similar to 3 x 10(39) ergs s(-1). The calculated quantiles for the extracted counts allow a broad range of temperatures but require a temperature hotter than 5 keV if there is no intrinsic absorption. The long-term light curve (1995-2005) declines as t(-2.6 +/- 0.6). This is one of the steepest X-ray light curves. The X-ray luminosity indicates that the emitting region has a high density (> 10(5) cm(-3)) and that the density profile is not consistent with a constant mass-loss stellar wind during the similar to 5000 yr before the explosion. If the circumstellar medium is due to progenitor mass loss, then the mass-loss rate is extremely high (similar to 10(-3) M-circle dot yr(-1) [v(w)/10 km s(-1)]). The X-ray results are compared with the predictions of models of SN 1988Z.