Non-Thermal and Supra-Thermal X-Rays from the Northeast Shell of W28

We observed the northeast X-ray shell of an SNR W28 with X M M N ew ton and found two X-ray bright spots; one is interacting with a molecular cloud, and the other is free from the interaction. The X-ray spectra from these regions show emission lines and a hard tail, and are fitted with a model of a thin-thermal plasma (k T ∼ 0.3 keV) plus a power-law function. The abundances are lower than the solar value, which suggests the presence of additional featureless continuum emission, possibly a non-thermal component. We also found that the hard X-rays are extending to the center region of the SNR (the inside region). The X-ray spectrum is different from those of the shell region; it requires three-temp erature (∼ 0.3, ∼ 0.6, and > 4 keV) plasma.