The links between magnetic fields and filamentary clouds III: field regulated mass cumulative functions

TL;DR

This paper investigates how magnetic field orientation influences the mass distribution and star formation efficiency in filamentary molecular clouds, revealing that field alignment affects cloud fragmentation and gas density.

Contribution

It demonstrates that magnetic field orientation regulates the mass cumulative function and star formation efficiency, extending previous work on cloud fragmentation.

Findings

Clouds aligned with magnetic fields have shallower mass cumulative functions.

Field orientation correlates with star formation efficiency.

Magnetic fields influence gas density distribution in molecular clouds.

Abstract

During the past decade the dynamical importance of magnetic fields in molecular clouds has been increasingly recognized, as observational evidence has accumulated. However, how a magnetic field affect star formation is still unclear. Typical star formation models still treat a magnetic fields as an isotropic pressure, ignoring the fundamental property of dynamically important magnetic fields: their direction. This study builds on our previous work which demonstrated how the mean magnetic field orientation relative to the global cloud elongation can affect cloud fragmentation. After the linear mass distribution reported earlier, we show here that the mass cumulative function (MCF) of a cloud is also regulated by the field orientation. A cloud elongated closer to the field direction tends to have a shallower MCF, in other words, a higher portion of the gas in high density. The evidence is consistent with our understanding of bimodal star formation efficiency discovered earlier, which is also correlated with the field orientations.