X-Ray Emission from Supernova Remnants Observed in the ASCA Galactic   Plane Survey
  X-ray images and spectra of 5 cataloged supernova remnants (SNRs), G12.0-0.1, G346.6-0.2, G348.5+0.1, G348.7+0.3, and G355.6-0.0, observed in the ASCA galactic plane survey are presented. The sizes of X-ray emission from G12.0-0.1, G348.5+0.1, G348.7+0.3, and G355.6-0.0 are comparable to their radio structures, while that of G346.6-0.2 is smaller than the radio structure. The X-ray spectra of all of the SNRs were heavily absorbed by interstellar matter with N_H>10^{22} cm^{-2}. The spectrum of G355.6-0.0 exhibited emission lines, indicating that the X-ray emission has a thin thermal plasma origin, and was well represented by two-temperature thin thermal emission model. On the other hand, no clear emission line features were found in the spectra of the others and the spectra could be represented by either a thin thermal emission model or a power-law model. 
Shigeo Yamauchi, Masaru Ueno, Katsuji Koyama, and Aya Bamba