High resolution spectroscopy and emission line imaging of DEM L 71 with XMM-Newton

Abstract

The X-ray emission from the supernova remnant DEM L71 is measured and analysed using the high-resolution cameras and spectrometers on board XMM-Newton. The spectrum from the outer shell is reproduced very well by two plasma components of kTe = 0.3 and 0.8 keV. The abundance value from this shell is consistent with the average LMC values. More extreme temperature variations are possibly indicated by spatial variations in the O VII forbidden/resonance line ratio, which could imply that in some regions the plasma is cooling dramatically and recombining. However, an alternative and equally interesting possibility is that the variation in forbidden/resonance ratios is due to resonant scattering, which would reduce resonance line emission along lines of sight with a high O VII column density. The inner region is hotter (kTe = 1.1 keV) and shows enhanced Fe and Si abundances. We estimate the Fe and Si ejecta mass to be 0.7-1.1 M⊙ and 0.1-0.15 M⊙, respectively. The morphology, mass estimates and abundances strongly suggest that DEM L 71 is the result of a type la explosion, as indicated by previous measurements.