Core mass function of a single giant molecular cloud complex with ~10^4 cores

TL;DR

This study analyzes the core mass function in the Cygnus X molecular cloud, finding a power-law distribution similar to the stellar initial mass function but with notable differences, suggesting the IMF may not directly derive from the CMF.

Contribution

The paper provides a detailed CMF derived from a large core sample in Cygnus X, and investigates the relationship between the CMF and IMF, challenging the idea of a simple core-to-star mass mapping.

Findings

CMF follows a power-law with slope -2.30 for masses up to 1300 M_sun

No clear low-mass turnover in the CMF, unlike the IMF

The similarity between CMF and IMF is not due to a direct core-to-star mapping

Abstract

Similarity in shape between the initial mass function (IMF) and the core mass functions (CMFs) in star-forming regions prompts the idea that the IMF originates from the CMF through a self-similar core-to-star mass mapping process. To accurately determine the shape of the CMF, we create a sample of 8,431 cores with the dust continuum maps of the Cygnus X giant molecular cloud complex, and design a procedure for deriving the CMF considering the mass uncertainty, binning uncertainty, sample incompleteness, and the statistical errors. The resultant CMF coincides well with the IMF for core masses from a few $M_{\odot}$ to the highest masses of 1300 $M_{\odot}$ with a power-law of ${\rm d}N/{\rm d}M\propto M^{-2.30\pm0.04}$, but does not present an obvious flattened turnover in the low-mass range as the IMF does. More detailed inspection reveals that the slope of the CMF steepens with increasing mass. Given the numerous high-mass star-forming activities of Cygnus X, this is in stark contrast with the existing top-heavy CMFs found in high-mass star-forming clumps. We also find that the similarity between the IMF and the mass function of cloud structures is not unique at core scales, but can be seen for cloud structures of up to several pc scales. Finally, our SMA observations toward a subset of the cores do not present evidence for the self-similar mapping. The latter two results indicate that the shape of the IMF may not be directly inherited from the CMF.