Discovery of New Interacting Supernova Remnants in the Inner Galaxy
  OH(1720 MHz) masers are excellent signposts of interaction between supernova
remnants(SNRs) and molecular clouds. Using the GBT and VLA we have surveyed 75
SNRs and six candidates for maser emission. Four new interacting SNRs are
detected with OH masers: G5.4-1.2, G5.7-0.0, G8.7-0.1 and G9.7-0.0. The newly
detected interacting SNRs G5.7-0.0 and G8.7-0.1 have TeV gamma-ray counterparts
which may indicate a local cosmic ray enhancement. It has been noted that
maser-emitting SNRs are preferentially distributed in the Molecular Ring and
Nuclear Disk. We use the present and existing surveys to demonstrate that
masers are strongly confined to within 50 degrees Galactic longitude at a rate
of 15 percent of the total SNR population. All new detections are within 10
degrees Galactic longitude emphasizing this trend. Additionally, a substantial
number of SNR masers have peak fluxes at or below the detection threshold of
existing surveys. This calls into question whether maser surveys of Galactic
SNRs can be considered complete and how many maser-emitting remnants remain to
be detected in the Galaxy.
