Suzaku study on the Ejecta of the Supernova Remnant G272.2$-$3.2

Abstract

We report re-analyses of the Suzaku observations of the Galactic supernova remnant (SNR), G272.2$-$3.2, for which the previous studies were limited below 3 keV. With careful data reduction and background subtraction, we discover the K-shell lines of Ar, Ca, and Fe above 3 keV. The X-ray spectrum of G272.2$-$3.2 consists of two components, a low-temperature collisional ionization equilibrium (CIE) plasma ($kT_{\rm e} \sim 0.2$ keV) and a high-temperature non-equilibrium ionization (NEI) plasma ($kT_{\rm e} = 0.6$-$3$ keV). The CIE plasma has solar abundances over the entire area, hence it would originate from the interstellar medium. On the other hand, the abundances of the NEI plasma increase toward the inner region, suggesting the ejecta origin. The line center energy of the Fe K-shell emission ($\sim 6.4$ keV) suggests that the ejecta are recently heated by the reverse shock, a common feature in Type Ia SNRs.