Size-mass diagram of the filamentary structures discussed in Sect. 5.1. The values are taken from the original publications. This diagram illustrates the differences discussed in the text between the filaments detected in this work and giant filamentary structures reported in the literature. The “Nessie” filament is represented by two connected circles; the left circle corresponds to the structure identified by Jackson et al. (2010) while the right circle corresponds to the large structure identified by Goodman et al. (2014). The solid magenta circles identify filaments associated with massive star forming tracers while the open circles identify the non-MSF filaments. The red dashed lines correspond to the critical mass per unit length above which the filament becomes unstable and will start to collapse along their radial axis (André et al. 2014); the upper and lower line corresponds to velocity dispersions of 1.2 and 0.7 km s^-1, respectively, and assume an isothermal temperature of 10 K.