Dense Outflowing Molecular Gas in Massive Star-forming Regions

Abstract

Dense outflowing gas, traced by transitions of molecules with large dipole moment, is important for understanding mass loss and feedback of massive star formation. HCN 3-2 and HCO${}^{+}$ 3-2 are good tracers of dense outflowing molecular gas, which are closely related to active star formation. In this study, we present on-the-fly (OTF) mapping observations of HCN 3-2 and HCO${}^{+}$ 3-2 toward a sample of 33 massive star-forming regions using the 10-m Submillimeter Telescope (SMT). With the spatial distribution of line wings of HCO${}^{+}$ 3-2 and HCN 3-2, outflows are detected in 25 sources, resulting in a detection rate of 76$\%$. The optically thin H${}^{13}$CN and H${}^{13}$CO${}^{+}$ 3-2 lines are used to identify line wings as outflows and estimate core mass. The mass $M_{out}$, momentum $P_{out}$, kinetic energy $E_K$, force $F_{out}$ and mass loss rate ${\dot{M}}_{out}$ of outflow and core mass, are obtained for each source. A sublinear tight correlation is found between the mass of dense molecular outflow and core mass, with an index of $\sim$ 0.8 and a correlation coefficient of 0.88.

22 pages, 5 figures, 4 tables, accepted in AJ

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