Detection of Infall Signatures toward Serpens SMM4

We present the detection of kinematic infall signatures towards the Class 0protostellar system SMM4 in the Serpens cloud core. We have observed the densemolecular gas towards the embedded source using millimeter and submillimeterline transitions of density sensitive molecular tracers. High signal-to-noiseratio maps obtained in HCO+ J=1-0, J=3-2, and J=4-3, and CS J=2-1 show theblue-bulge infall signature. The blue-bulge infall signature can be observed inthe centroid velocity maps of protostellar objects when infall dominates overrotation. The line profiles of HCO+ and CS exhibit the characteristic blueasymmetric line profile signature consistent with infall. In addition, HCO+ andCS optical depth profiles obtained using isotopic observations show a redasymmetry also consistent with an infall interpretation. Usingthree-dimensional radiative transfer models based on the rotating, collapsemodel of Terebey, Shu and Cassen, we derive infall parameters of the source. Todetermine the direction and orientation of molecular outflows in the largerSerpens cluster, wide-field mapping of CO J=1-0 emission was also performed.Comment: 27 pages, 7 figures, to appear in Ap