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J. Vink (Columbia University), J. M. Laming (NRL), M. F. Gu, A. Rasmussen (MIT), J. S. Kaastra (SRON, Utrecht)
We will present new evidence for slow temperature and ionization equilibration behind the shock of SN 1006, based on XMM-Newton high resolution spectroscopy of a bright, compact knot (0.4\arcmin) at the northwestern edge of the remnant. The evidence consists of the detection of thermal Doppler broadening of O VII line emission, as observed with the Reflective Grating Spectrometer. The observed line width of \sigma = (3.4±0.5)\times 10-3 keV at a line energy of 0.57 keV indicates an oxygen temperature of kT = 528 ±150 keV. Combined with the observed electron temperature of ~1.5 keV the observed broadening is direct evidence for temperature non-equilibration in high Mach number shocks, and slow subsequent equilibration. The O~VII line emission allows an accurate determination of the ionization state of the plasma, which is characterized by a relatively high forbidden line contribution, indicating \log(n\rm e) t ~q 9.2.
JV and MFG were supported for this work by the NASA through Chandra Postdoctoral Fellowship Award Numbers PF0-10011 & PF0-10014 issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-39073. JML was supported by the NASA Contract S 92540F from the XMM GI Program and by basic research funds of the Office of Naval Research.
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Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.