A Chandra ACIS Observation of the X-ray Luminous SN1988Z

Abstract

SN1988Z is the most luminous X-ray-emitting supernova, initially detected in 1995 using the ROSAT HRI with a luminosity of ~8x10^40 erg 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 SN1988Z using the ACIS detector on Chandra. We readily detect SN1988Z, obtaining ~30 net counts which corresponds to a 0.2-2 keV luminosity of ~3.2x10^39 erg 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 ~5000 years before the explosion. If the circumstellar medium is due to progenitor mass loss, then the mass loss rate is extremely high (~10^-3 M_sol yr^-1(v_w / 10 km s^-1)). The X-ray results are compared with the predictions of models of SN1988Z.