On filament fragmentation and the impact of ambient environment on it

Abstract

Filaments are crucial intermediaries in the star formation process. Recent observations of filaments show that - \textbf{(i)} a number of them are non-singular entities, and rather a bundle of velocity coherent fibres, and \textbf{(ii)} while a majority of filaments spawn cores narrower than their natal filaments, some cores are broader. We explore these issues by developing hydrodynamic simulations of an initially sub-critical individual filament that is allowed to accrete gas from its neighbourhood and evolves under self-gravity. Results obtained here support the idea that fibres form naturally during the filament formation process. We further argue that the ambient environment, i.e., the magnitude of external pressure, and not the filament linemass alone, has bearing upon the morphology of its evolution. We observe that a filament is susceptible to the \emph{sausage}-type instability irrespective of the external pressure. The fragments, however, are pinched in a filament experiencing pressure comparable to that in the Solar neighbourhood ($\sim 10^4$ K cm${}^{-3}$). By contrast, fragments are broad and spherical - having density profiles similar to that of a stable Bonnor - Ebert sphere - when the filament experiences a higher pressure, typically $\ge 10^5$ K cm${}^{-3}$, but $\le 10^6$ K cm${}^{-3}$). The filament tends to rupture at even higher external pressure ($\ge 10^7$ K cm${}^{-3}$). These observations collectively mean that star formation is less efficient with increasing external pressure.

19 pages, 14 figures; To appear in MNRAS; Fig. 2f has been revised slightly after an error was found in the earlier version

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Cited by in corpus (4)

• Witnessing the fragmentation of a filament into prestellar cores in Orion B/NGC 2024
• Core formation via filament fragmentation and the impact of ambient pressure on it
• ArTéMiS imaging of the filamentary infrared dark clouds G1.75-0.08 and G11.36+0.80: Dust-based physical properties of the clouds and their clumps
• A High-Mass Young Star-forming Core Escaping from Its Parental Filament