Far‐Ultraviolet and X‐Ray Observations of the Reverse Shock in the Small Magellanic Cloud Supernova Remnant 1E 0102.2−7219

We present FUSE and XMM-Newton data for the reverse shock of the O-rich SNR1E0102.2-7219 in the SMC. The FUSE observations cover three regions withsignificantly different optical [O III] intensities, all associated with therelatively bright part of the X-ray ring. Emission lines of O VI 1032, 1038 areclearly detected in the FUSE spectra. By combining this O VI doublet emissionwith the O VII triplet and O VIII Lyalpha fluxes from the XMM-Newton spectraand assuming a non-equilibrium ionization model with a single ionizationtimescale for the spectra, we are able to find a narrow range of temperaturesand ionization timescales that are consistent with the respective line ratios.However, if we assume a plane-parallel shock model with a distribution ofionization timescales, the O VI emission appears to be inconsistent with O VIIand O VIII in X-rays. We also analyze the total XMM-Newton EPIC-MOS 1/2 spectrafor the three regions. The X-ray spectra are dominated by strong emission linesof O, Ne, and Mg, however, we detect an emission component that accounts for 14- 25% of the flux and can be attributed to shocked ISM. We find that there isno consistent set of values for the temperature and ionization timescale whichcan explain the observed line ratios for O, Ne, and Mg. This would beconsistent with a structured distribution of the ejecta as the O, Ne, Mg wouldhave interacted with the reverse shock at different times.Comment: 28 pages, 5 figues, Fig. 1 as JPEG. To be published in ApJ (01 May 2006, v. 642, 1 issue