The Core Mass Function in the Infrared Dark Cloud G28.37+0.07

Abstract

Abstract In this paper, we analyze the 1.3 mm continuum ALMA data that cover the majority of the infrared dark cloud (IRDC) G28.37+0.07. With a spatial resolution of 0.″5 (2500 au at 5 kpc), the continuum image reveals five groups of dense cores. Each core group has a projected physical scale of about 1 pc, with core masses spanning a dynamic range of about 100. We use the dendrogram method (astrodendro) and a newly developed graph method (astrograph) to identify individual cores. The core masses are estimated through the millimeter continuum flux, assuming constant temperature and using an NH3-based gas temperature. We construct core mass functions (CMFs) based on the two methods and fit a power-law relation dN/d log M ∝ M −α to the CMFs for M > 0.79 M ⊙. In the constant-temperature scenario, astrograph gives α = 0.80 ± 0.10, while astrodendro gives α = 0.71 ± 0.11, both significantly shallower than the Salpeter-type initial mass function with α = 1.35. In the scenario where the NH3 gas temperature is applied to cores, astrograph gives α = 1.37 ± 0.06, while astrodendro gives α = 0.87 ± 0.07. Regional CMF slope variation is seen between the core groups. We also compare CMFs in three different environments, including IRDC G28.37+0.07, IRDC clumps, and G286.21+0.17, using the identical dendrogram method. Results show that IRDCs have smaller α than the cluster-forming cloud G286.21+0.17.