Progenitor type identification for supernova remnant N103B in the Large Magellanic Cloud by Suzaku and Chandra observations

This paper presents a detailed analysis of supernova remnant (SNR) N103B located in the Large Magellanic Cloud (LMC), based on Suzaku and Chandra observations. The spectrum of the entire remnant was closely reproduced by using three interstellar medium (ISM) components with temperatures of ∼ 0.32, ∼ 0.56, and ∼ 0.92 keV and one ejecta component with ∼ 3.96 keV, based on a spectral analysis of the Suzaku/X-ray Imaging Spectrometer (XIS) data. The ejecta was overabundant in heavy elements, such as Mg, Si, S, Ca, Fe, and Ni. The unprecedentedly high quality of data obtained with Suzaku/XIS allowed us to correctly distinguish between two emissions from the ISM and the ejecta for the first time in a spectral analysis. Combining the spectral analysis of XIS data with the image analysis based on Chandra/Advanced CCD Imaging Spectrometer (ACIS) data, we verified that the ejecta distributions for elements from Si to Fe-K were similar to one another, although the Fe-K emission was located slightly inward compared with that of the lighter elements such as Si, S, Ar, and Ca. We compared hydrogen-rich ejecta plasma (called "H-dominated plasma"), which is indicative of Type II SNRs, with plasma rich in heavy elements and poor in hydrogen (called "pure metal plasma") mainly observed in Type Ia SNRs. High-energy continuum images in the 5.2-6.0 keV band obtained with ACIS were extremely similar to those of the ejecta, implying that the origin of the high-energy continuum might indeed be the ejecta. By combining spectral analyses and high-energy continuum images, we found some indications for H-dominated plasma, and showed, that the progenitor of N103B might have been a Type II supernova. The progenitor mass was estimated to be 13 M_⊙ based on the abundance patterns of Mg, Fe, and Ni relative to Si.