Large-scale properties of the clump mass function

The mass function of molecular cloud clumps and cores is widely used to compare the results of numerical simulations with the observations adopting different prescriptions for star formation. However, our ability to test different theories relies critically on our ability to measure it accurately and interpret it confidently. From an observational perspective, mass functions are subject to uncertainties due to differences in the sample selection, data reduction, and analysis techniques. To reduce these and other biasing effects, in this work we discuss methods to construct clusters or groups of sources extracted from the Hi-GAL survey, which allows us to look at large clump populations in various clouds with different physical conditions. We then construct the clump mass function of each separate group, and we fit the clump mass functions with the two most widely used functional forms, power law, and lognormal. The best-fitting parameters show no correlation with distance and positional parameters of the groups, and the mass spectra appear to have similar shapes and overall widths, though with different intrinsic mass scales. The statistical invariance of the shape of the CMF suggests that no significant differences exist in the early phases between regions dominated by low- and high-mass star formation. Finally, we found that high-mass star formation is more likely to happen in groups where the range of clump mass is shifted towards the high-mass end