Upper: mass per unit length (Mlin ) of the OMC-1 (blue dots) and OMC-2 (red dots) fibers as function of their internal non-thermal velocity dispersion normalized by the local sound speed (σNT ∕cs(TK)). This plot includes the expected critical masses (mcrit ) for an infinite filament in hydrostatic equilibrium at temperatures of 10 K (thick dashed line), 20 K (dashed-dotted line), and 30 K (thick dotted line), respectively (see Eq. (3)). Lower: individual critical mass ratio (Mlin/mcrit) for all the fibers in OMC-1 (blue) and OMC-2 (red). For every single fiber the critical mass ratio is calculated relative to its local mcrit (TK, σNT). The error bars indicate the factor of two uncertainties associated to our Mlin estimates.