A pan-galaxy study of synthetic giant molecular filaments: a turbulence-dominated life cycle

Abstract

Recent surveys of the Galactic plane have revealed dozens of giant molecular filaments (GMFs), with lengths ranging from tens to hundreds of parsecs, yet their origins and life cycles remain debated. In this work, we analyze over 700 GMFs identified from synthetic CO emission maps of a high-resolution magnetohydrodynamic simulation of a Milky Way-like galaxy, whose lengths range from $\sim 10$ pc to $\sim 300$ pc. We find that turbulent shock from galactic shear and stellar feedback are the primary drivers of GMF formation. Magnetized turbulence dominates their internal dynamics, supporting the filaments against global collapse while simultaneously inducing fragmentation into dense clumps. This fragmentation follows the turbulence-driven sausage instability model, rather than pure Jeans instability, and triggers efficient star formation along the filaments. Cloud-cloud collisions are frequent, affecting more than $70\%$ of GMFs, and often disrupt or reshape their morphology. The typical filamentary lifetime is $t_{\text{fil}} \sim 14$ Myr, comparable to the crossing time of giant molecular clouds (GMCs). The molecular gas half-life is $\sim 7$ Myr, similar to that of GMCs, indicating that GMFs are transient but dynamically important structures.