the highest signals are likely contaminated by remaining contribution from galaxies, we remove the 10$\%$ highest and lowest signal filaments to determine the mean. The resulting values are given in Table \[tab:uvbsigs\], together with the standard deviation of the cut distribution. For reference, we also give the corresponding HI column density over a 100 km $\mathrm{s}^{-1}$ velocity width. These values are consistent with the lower-density gas found through HI absorption measurements at low redshift [e.g., @art:teppergarcia12]. The last column in Table \[tab:uvbsigs\] presents the column density based on the mean signal in the brightest 10 per cent of the cells in filaments in the simulation box. This shows that a significant fraction of the IGM gas in the filaments has densities one or two orders of magnitude higher than the mean and can thus also result in a stronger signal.\

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  UVB model     $\Gamma_{\rm HI}$ at $z$=0     $<\delta T_{\rm b}^{\rm HI}>_{\rm fil}$   $N_{\rm HI}^{\rm all}$   $N_{\rm HI}^{10 \%}$
               ($10^{-14}\,\mathrm{s}^{-1}$)                ($10^{-7}$ K)                      (cm$^-2$)               (cm$^-2$)
                            2.3                                $6\pm6$                      $1\times10^{14}$        $2\times10^{16}$
                            6.1                                $2\pm2$                      $4\times10^{13}$        $8\times10^{15}$
                            8.4                                $2\pm2$                      $3\times10^{13}$        $5\times10^{15}$
  ----------- ------------------------------- ----------------------------------------- ------------------------ ----------------------

  : Estimated mean filament signals $<\delta T_{\rm b}^{\rm HI}>_{\rm fil}$ of the Bisous filaments for the 