On the spatial distributions of stars and gas in numerical simulations of molecular clouds

TL;DR

This study compares the spatial distributions of stars and gas in molecular cloud simulations using the $ ext{Q}$-parameter, revealing that stars are substructured while gas is smooth, with no significant difference due to feedback processes.

Contribution

It introduces a self-consistent method to compare star and gas distributions using the $ ext{Q}$-parameter in simulations, highlighting the complex relationship between gas and star structures.

Findings

Stars are substructured with $ ext{Q} ext{~} 0.4-0.7$

Gas is smooth with $ ext{Q} ext{~} 0.9$

No significant difference in gas structure with or without feedback

Abstract

We compare the spatial distribution of stars which form in hydrodynamical simulations to the spatial distribution of the gas, using the $\mathcal{Q}$-parameter. The $\mathcal{Q}$-parameter enables a self-consistent comparison between the stars and gas because it uses a pixelated image of the gas as a distribution of points, in the same way that the stars (sink particles in the simulations) are a distribution of points. We find that, whereas the stars have a substructured, or hierarchical spatial distribution ($\mathcal{Q} \sim 0.4 - 0.7$), the gas is dominated by a smooth, concentrated component and typically has $\mathcal{Q} \sim 0.9$. We also find no statistical difference between the structure of the gas in simulations that form with feedback, and those that form without, despite these two processes producing visually different distributions. These results suggest that the link between the spatial distributions of gas, and the stars which form from them, is non-trivial.