The Core Mass Function across Galactic Environments. II. Infrared Dark Cloud Clumps

Journal article, 2018

We study the core mass function (CMF) within 32 dense clumps in seven infrared dark clouds (IRDCs) with the Atacama Large Millimeter/submillimeter Array via 1.3 mm continuum emission at a resolution of similar to 1 ''. We have identified 107 cores with the dendrogram algorithm, with a median radius of about 0.02 pc. Their masses range from 0.261 to 178 M-circle dot. After applying completeness corrections, we fit the combined IRDC CMF with a power law of the form dN/d log M proportional to M(-alpha)and derive an index of alpha similar or equal to 0.86 +/- 0.11 for M >= 0.79 M-circle dot and alpha similar or equal to 0.70 +/- 0.13 for M >= 1.26 M-circle dot, which is a significantly more top-heavy distribution than the Salpeter stellar initial mass function index of 1.35. We also make a direct comparison of these IRDC clump CMF results to those measured in the more evolved protocluster G286 derived with similar methods, which have alpha similar or equal to 1.29 +/- 0.19 and 1.08 +/- 0.27 in these mass ranges, respectively. These results provide a hint that, especially for the M >= 1.26 M-circle dot range where completeness corrections are modest, the CMF in high pressure, early-stage environments of IRDC clumps may be top-heavy compared to that in the more evolved, global environment of the G286 protoclusters. However, larger samples of cores probing these different environments are needed to better establish the robustness of this potential CMF variation.