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Observations of SN 1987A by the Chandra High Energy Transmission Grating(HETG) in 1999 and the XMM-Newton Reflection Grating Spectrometer (RGS) in 2003show very broad (v-b) lines with a full-width at half-maximum (FWHM) of order10^4 kms; at these times the blast wave was primarily interacting with the HIIregion around the progenitor. Since then, the X-ray emission has beenincreasingly dominated by narrower components as the blast wave encountersdense equatorial ring (ER) material. Even so, continuing v-b emission is seenin the grating spectra suggesting that interaction with HII region material ison-going. Based on the deep HETG 2007 and 2011 data sets, and confirmed by RGSand other HETG observations, the v-b component has a width of 9300 +/-2000 kmsFWHM and contributes of order 20% of the current 0.5--2 keV flux. Guided bythis result, SN 1987A's X-ray spectra are modeled as the weighted sum of thenon-equilibrium-ionization (NEI) emission from two simple 1D hydrodynamicsimulations, this "2x1D" model reproduces the observed radii, light curves, andspectra with a minimum of free parameters. The interaction with the HII region(rho_init \sim 130 amu/cc, +/- 15 degrees opening angle) produces thevery-broad emission lines and most of the 3-10 keV flux. Our ER hydrodynamics,admittedly a crude approximation to the multi-D reality, gives ER densities oforder 10^4 amu/cc, requires dense clumps (x5.5 density enhancement in \sim 30%of the volume), and it predicts that the 0.5-2 keV flux will drop at a rate of\sim 17% per year once no new dense ER material is being shocked.

Evolution and Hydrodynamics of the Very-Broad X-ray Line Emission in SN 1987A