AChandraACIS Observation of the X‐Ray–luminous SN 1988Z

SN1988Z is the most luminous X-ray-emitting supernova, initially detected in1995 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 blastwave into an especially dense circumstellar medium. In this paper, we describea recent observation of SN1988Z using the ACIS detector on Chandra. We readilydetect SN1988Z, obtaining ~30 net counts which corresponds to a 0.2-2 keVluminosity of ~3.2x10^39 erg s^-1. The calculated quantiles for the extractedcounts allow a broad range of temperatures, but require a temperature hotterthan 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 lightcurves. The X-ray luminosity indicates that the emitting region has a highdensity (>10^5 cm^-3) and that the density profile is not consistent with aconstant mass loss stellar wind during the ~5000 years before the explosion. Ifthe circumstellar medium is due to progenitor mass loss, then the mass lossrate is extremely high (~10^-3 M_sol yr^-1(v_w / 10 km s^-1)). The X-rayresults are compared with the predictions of models of SN1988Z.Comment: accepted ApJ; 11 manuscript pages, 3 figure