A search for 22-GHz water masers within the giant molecular cloud associated with RCW 106

Abstract

We report the results of a blind search for 22-GHz water masers in two regions, covering approximately half a square degree, within the giant molecular cloud associated with RCW 106. The complete search of the two regions was carried out with the 26-m Mount Pleasant radio telescope and resulted in the detection of nine water masers, five of which are new detections. Australia Telescope Compact Array (ATCA) observations of these detections have allowed us to obtain positions with arcsecond accuracy, allowing meaningful comparison with infrared and molecular data for the region. We find that for the regions surveyed there are more water masers than either 6.7-GHz methanol, or main-line OH masers. The water masers are concentrated towards the central axis of the star formation region, in contrast to the 6.7-GHz methanol masers which tend to be located near the periphery. The colours of the GLIMPSE point sources associated with the water masers are similar to those of 6.7-GHz methanol masers, but slightly less red. We have made a statistical investigation of the properties of the (CO)-C-13 and 1.2-mm dust clumps with and without associated water masers. We find that the water masers are associated with the more massive, denser and brighter (CO)-C-13 and 1.2-mm dust clumps. We present statistical models that are able to predict those (CO)-C-13 and 1.2-mm dust clumps that are likely to have associated water masers, with a low misclassification rate.