Spectral properties of nonthermal X-ray emission from the shell-type SNR RX J1713.7-3946 as revealed by XMM-Newton

We present the results of our morphological and spectral study of the properties of the supernova remnant RX J1713.7- 3946 based on data obtained with XMM-Newton. Highly inhomogeneous structures, such as the bright spots, filaments, and dark voids noted by Uchiyama et al. ( 2003), appear in the entire bright western portion of the shell. In addition two narrow rims are found which run parallel to each other from north to south in the western part of the remnant. No complex structures are seen in the interior region of the remnant. The X-ray spectra everywhere can be well represented by a power-law function with photon index in the range within Gamma = 2.0 - 2.8. A clear difference between spectra of the central dim region and of the bright western portion is seen at lower energies. This difference can be ascribed either to an additional thermal component in the center with electron temperature kT(e) = 0.56 keV or, alternatively, to an increase in column density by DeltaN(H) similar to 0.3 x 10(22) cm(-2) in the western region. In the context of the recent discovery by the NANTEN telescope of a molecular cloud apparently interacting with the western part of the supernova remnant the second possibility seems to be the more likely scenario.