Suzaku Observation of 30 Dor C: A Supernova Remnant with the Largest Non-Thermal Shell

Abstract

This paper reports on the Suzaku results of thermal and non-thermal features of 30 Dor C, a supernova remnant (SNR) in a superbubble of the Large Magellanic Cloud (LMC). The west rim exhibits a non-thermal X-ray spectrum with no thermal component. A single power-law model is rejected, but a power-law model with spectral cutoff is accepted. The cutoff frequency of (3–7) $\times$ 10$^{17}$Hz is the highest among the shell-type SNRs, like SN 1006 ($\sim$6 $\times$ 10$^{16}$Hz), and hence 30 Dor C would be the site of the highest energy accelerator of the SNR shock. The southeast (SE) and northeast (NE) rims have both thermal and non-thermal components. The thin-thermal plasmas in both rims are in a collisional ionization equilibrium state. The electron temperature of the plasma in the SE rim ($kT_{\rm e}$$\sim$ 0.7 keV) is found to be higher than the previously reported value. The power-law index from SE is nearly the same, while that from the NE is larger than that of the West rim. The SNR age would be in the range of (4–20) $\times$ 10$^{3}$yr. Thus, 30 Dor C is likely to be the oldest shell-like SNR with non-thermal emission.