The role of accretion and extended SiO emission in forming high mass protocluster NGC 6334-V

Most stars form within the massive clumps which are embedded in the filamentary molecular clouds. Characterizing how the material is accreted from the filaments to the clusters, and from the clusters onto the cluster members is a long standing problem. We study observationally the formation of the massive protocluster NGC 6334-V embedded in filamentary cloud NGC6334 to investigate the manner of accretion using different molecular tracers. We used ALMA observations at 3 mm in continuum and different dense gas tracers like HCN and HCO+ isotopologues and reveal protocluster NGC 6334-V on small scale. Comparing the intermediate scale ALMA data with the large scale APEX data shows a clear correlation between both scales. In order to reliably identify the filaments, we applied DisPerse to the APEX and ALMA data. All identified filaments are converging to the center of the protocluster where a density cavity is located. The extended SiO is appeared on where the filaments converge in the central hubs. The SiO molecular emission reveals widespread and a shell-like morphology. The narrow lines on SiO spectrum tracing slow shocks are likely with the accretion process into the cores. These observations suggest that the filaments on small scale ALMA observations follow the same pattern as seen in large scale APEX observations and indicate how the gas falls from large scale NGC 6334 cloud into the small scale protocluster through distinctive converging flows. Moreover, the spectacular extended morphology of SiO with narrow Gaussian line profile explains the presence of low-velocity shock from colliding flows and outflow process together. However, based on our data the cloud-cloud collision is more dominant.