A 6.7 GHz Methanol Maser Survey. II. Low Galactic Latitudes

Abstract

Abstract We report the results of our systematic survey for Galactic 6.7 GHz Class II CH3OH maser emission toward a sample of young stellar objects. The survey was conducted with the Shanghai Tianma Radio Telescope (TMRT). The sample consists of 3348 sources selected from the all-sky Wide-field Infrared Survey Explorer (WISE) point-source catalog. We discussed the selection criteria in detail and the detection results of those at high Galactic latitudes (i.e., ) in a previous paper (Yang et al. 2017). Here, we present the results from the survey of those at low Galactic latitudes, i.e., . Of 1875 selected WISE point sources, 291 positions that were actually associated with 224 sources that were detected with CH3OH maser emission. Among them, 32 are newly detected. A majority of the newly detected sources are associated with bright WISE sources. The majority of the detected sources (209/224 = 93.3%) are quite close to the Galactic Plane ( ) and lie on the inner spiral arms with positive local standard of rest velocities. The detection rate and the color–color distribution of our detection are all matched with our anticipation. Combining with detections from previous surveys, we compile a catalog of 1085 sources with 6.7 GHz CH3OH maser emission in our Galaxy.