Panel a: H₂ column density image of the Serpens filament obtained from the Herschel Gould belt survey. The contours correspond to column densities of 6 × 10²¹ cm⁻², 8 × 10²¹ cm⁻², and 1 × 10²² cm⁻². The extracted crest of the Serpens filament is shown with the blue line. The emission within the white box is used to derive the radial profile of H₂ column density. The three black crosses give the positions of the three embedded YSOs. The beam size is shown in the lower right. Panel b: mean radial profile of H₂ column densities within the white box in panel a. The offsets increase from east to west. A Gaussian fit is indicated by the red line. Panel c: mean radial H₂ column density profile on the west (yellow) and east (orange) sides of the crest. The red and blue dashed lines represent Plummer-like fits to the east and west (see panel a) within a radius range of <0.2 pc, while the cyan and black lines represent the beam-convolved radial profile of Musca-West (Kainulainen et al. 2016) and the Serpens South filament (Kirk et al. 2013). In both panels a and b, the beam size is shown by the brown line.