Filament Accretion and Fragmentation in the Perseus Molecular Cloud

TL;DR

This study analyzes filament growth and core formation in the Perseus Molecular Cloud using ammonia observations, revealing that filaments grow via accretion and continuously form cores, influenced by their environment rather than gravity alone.

Contribution

It provides one of the first large-scale observational analyses of filament accretion and fragmentation, highlighting environmental effects on core formation in star-forming filaments.

Findings

Significant correlation between velocity gradient and filament properties.

Filaments grow through accretion and form cores continuously.

Velocity gradient orientation is not correlated with filament properties.

Abstract

Observations suggest that filaments in molecular clouds can grow by mass accretion while forming cores via fragmentation. Here we present one of the first large sample studies of filament accretion using velocity gradient measurements of star-forming filaments on the $\sim 0.05$ pc scale with NH$_3$ observations of the Perseus Molecular Cloud, primarily obtained as a part of the GBT Ammonia Survey (GAS). In this study, we find significant correlations between velocity gradient, velocity dispersion, mass per unit length, and the number of cores per unit length of the Perseus filaments. Our results suggest a scenario in which filaments not only grow through mass accretion but also form new cores continuously in the process well into the thermally supercritical regime. Such behavior is contrary to that expected from isolated filament models but consistent with how filaments form within a more realistic cloud environment, suggesting that the cloud environment plays a crucial role in shaping core formation and evolution in filaments. Furthermore, even though velocity gradients within filaments are not oriented randomly, we find no correlation between velocity gradient orientation and the filament properties we analyzed. This result suggests that gravity is unlikely the dominant mechanism imposing order on the $\sim 0.05$ pc scale for dense star-forming gas.