Giant molecular filaments in the Milky Way

Throughout the Milky Way, molecular clouds typically appear filamentary and mounting evidence indicates that this morphology plays an important role in star formation. What is not known is to what extent the dense filaments most closely associated with star he Milky Way's spiral structure? Using archival Galactic plane survey data, we have used multiple datasets in search of large-scale.velocity-coherent filaments in the Galactic plane. In this paper, we present our methods employed to identify coherent filamentary (GMFs) that have lengths on the order of similar to 100 pc, total masses of 10(4)-10(5) M-circle dot, and exhibit velocity coherence over their full length. The GMFs we study appear to be inter arm clouds and may be the Milky Way analogs to spurs observed in nearby spiral galaxies. We find that between 2 and 12% of the total mass (above similar to 10(20) cm(-2)) is dense (above 1022 cm 2) where filaments near spiral arms in the Galactic rnidplane tend to have higher dense gas mass fractions than those further from the arms