Submillimeter-wave and millimeter-wave observations of the interaction of supernova remnants with molecular clouds

We report on submillimeter-wave and millimeter-wave observations toward supernova remnants (SNRs) by using the James Clerk Maxwell Telescope, the Mt. Fuji submillimeter-wave telescope, and the Nobeyama 45-m radio telescope. For the supernova remnant W28, which is an EGRET gamma-ray source, we have convincingly detected the broad CO, $HCO+,$ HCN, and SiO emission lines from the shock-accelerated gas due to the SNR-cloud interaction. The previously-reported 1720-MHz OH maser spot is found to be located at the shock front. By using the Mt. Fuji submillimeter-wave telescope, we observed the 492-GHz CI (neutral atomic carbon), 345-GHz CO (3–2) and 330-GHz $13CO$ (3–2) emission toward SNRs, W44 and W51B/C. We found that the CI/CO and $CI/13CO$ intensity ratio tends to be high in the SNR-cloud interaction region in W51B/C SNR. This fact might suggest the CI relative abundance is enhanced by the interaction, not only in the SNR IC 443, but also in W51B/C SNR.