Supernova Remnants in the Magellanic Clouds. VI. The DEM L316 Supernova Remnants

The DEML316 system contains two shells, both with the characteristicsignatures of supernova remnants (SNRs). We analyze Chandra and XMM-Newton datafor DEML316, investigating its spatial and spectral X-ray features. Our Chandraobservations resolve the structure of the northeastern SNR (Shell A) as abright inner ring and a set of "arcs" surrounded by fainter diffuse emission.The spectrum is well fit by a thermal plasma model with temperature ~1.4 keV;we do not find significant spectral differences for different regions of thisSNR. The southwestern SNR (Shell B) exhibits an irregular X-ray outline, with abrighter interior ring of emission including a bright knot of emission. Overallthe emission of the SNR is well described by a thermal plasma of temperature~0.6 keV. The Bright Knot, however, is spectrally distinct from the rest of theSNR, requiring the addition of a high-energy spectral component consistent witha power-law spectrum of photon index 1.6--1.8. We confirm the findings of Nishiuchi et al. (2001) that the spectra of theseshells are notably different, with Shell A requiring a high iron abundance fora good spectral fit, implying a Type Ia origin. We further explicitly compareabundance ratios to model predictions for Type Ia and Type II supernovae. Thelow ratios for Shell A (O/Fe of 1.5 and Ne/Fe of 0.2) and the high ratios forShell B (O/Fe of 30--130 and Ne/Fe of 8--16) are consistent with Type Ia andType II origins, respectively. The difference between the SNR progenitor typescasts some doubt on the suggestion that these SNRs are interacting with oneanother.Comment: Accepted for ApJ v. 635 (December issue