The relation between water maser and CO outflow in strong far infrared sources

Abstract

A selected set of 56 IRAS point sources with 100 μm flux > 500 Jy were searched for H 2O maser emission at 22 GHz, usingthe 13.7 m telescope at Qinghai Observing Station. 11 new masers were found (Table 2). A statistical analysis is made on our and others' data of H 2O masers and CO outflows. We found: 1) The mechanical luminosities of CO outflow, L mCO, are correlated with the far infrared luminosities, L FIR, and are anti-correlated with the with the infrared spectral indices S 12–60. 2) The integrated luminosities of H 2O masers are also correlated with L FIR, and are not correlated with S 12–60. 3) For a given L mCO, there is a lower bound to L H 2O . The largest L mCO corresponds to the largest L H 2O . 4) The detection rates of both H 2O masers and CO outflows increase with increasing L FIR. 5) The distribution of S is more restricted to smaller values for the CO outflows and more extended for H 2O masers. 6) In general, there are more H 2O masers than CO outflows, and the detection rate of H 2O masers in known CO ouflows is higher than that of Co outflows in known H 2O masers. It is shown that these results can be understood in terms of the circumstances that surround the formation of large mass stars.