$\rm^{13}CO$ Filaments in the Taurus Molecular Cloud

TL;DR

This study identifies filamentary structures in the Taurus molecular cloud using $ m^{13}CO$ data, revealing broader widths and complex velocity structures, suggesting many are gravitationally unbound and highlighting differences from Herschel filament analyses.

Contribution

First detailed analysis of $ m^{13}CO$ filaments in Taurus with strict criteria, showing broader widths and complex velocity structures compared to previous Herschel results.

Findings

Only 10 filaments meet strict criteria in integrated maps.

Filament widths peak at 0.4 pc, broader than Herschel's 0.1 pc.

Velocity-coherent filaments have widths peaking at 0.2 pc.

Abstract

We have carried out a search for filamentary structures in the Taurus molecular cloud using $\rm^{13}CO$ line emission data from the FCRAO survey of $\rm \sim100 \, deg^2$. We have used the topological analysis tool, DisPerSe, and post-processed its results to include a more strict definition of filaments that requires an aspect ratio of at least 3:1 and cross section intensity profiles peaked on the spine of the filament. In the velocity-integrated intensity map only 10 of the hundreds of filamentary structures identified by DisPerSe comply with our criteria. Unlike Herschel analyses, which find a characteristic width for filaments of $\rm \sim0.1 \, pc$, we find a much broader distribution of profile widths in our structures, with a peak at 0.4 pc. Furthermore, even if the identified filaments are cylindrical objects, their complicated velocity structure and velocity dispersions imply that they are probably gravitationally unbound. Analysis of velocity channel maps reveals the existence of hundreds of `velocity-coherent' filaments. The distribution of their widths is peaked at lower values (0.2 pc) while the fluctuation of their peak intensities is indicative of stochastic origin. These filaments are suppressed in the integrated intensity map due to the blending of diffuse emission from different velocities. Conversely, integration over velocities can cause filamentary structures to appear. Such apparent filaments can also be traced, using the same methodology, in simple simulated maps consisting of randomly placed cores. They have profile shapes similar to observed filaments and contain most of the simulated cores.