Hung-Lin Liao(Department of Earth Science, NTNU); Yueh-Ning Lee(Department of Earth Science, NTNU)
The density probability density function (PDF) is a widely used tool to investigate the structures of molecular clouds and the underlying physics. Simulations and analytical models have suggested that the hierarchical structures, resulting from turbulent motion, produce a lognormal PDF with a power-law tail at high density due to self-gravity. The aim of this project is to find out the characteristic scale of gravitational collapse. Using the dendrogram, we identify the dense, gravitationally collapsing substructures in molecular clouds. Then we average the density of every substructure to filter out the gravitational contribution. We vary the leaf size of dendrogram i.e., the size of substructure, to detect the characteristic scale. We apply this approach on both column density PDF and density PDF to analyze the effect of self-gravity on density structure of molecular clouds and star formation process.