We characterize in detail the two∼ 0.3 pc long filamentary structures found within the subsonic region of Barnard 5. We use combined Robert C. Byrd Green Bank Telescope and Very Large Array observations of the molecular lines NH 3 (1, 1) and (2, 2) at a resolution of 1800 au, as well as James Clerk Maxwell Telescope continuum observations at 850 and 450 μm at a resolution of 4400 and 3000 au, respectively. We find that both filaments are highly supercritical with a mean mass per unit length, M/L, of∼ 80 M⊙ pc− 1 after background subtraction, with local increases reaching values of∼ 150 M⊙ pc− 1. This would require a magnetic field strength of∼ 500 μG to be stable against radial collapse. We extract equidistant cuts perpendicular to the spine of the filament and fit a modified Plummer profile as well as a Gaussian to each of the cuts. The filament widths (deconvolved FWHM) range between 6500 and 7000 au (∼ 0.03 pc) along the filaments. This equals∼ twice the radius of the flat inner region. We find an anticorrelation between the central density and this flattening radius, suggestive of contraction. Further, we also find a strong correlation between the power-law exponent at large radii and the flattening radius. We note that the measurements of these three parameters fall in a plane and derive their empirical relation. Our high-resolution observations provide direct constraints on the distribution of the dense gas within supercritical filaments showing pre-and protostellar activity.