Black: average radial X-ray profile of 15 165 filaments in the ROSAT R5 band. The 1σ uncertainties estimated by a bootstrap resampling are shown in gray. Cyan: average radial X-ray profile from 1000 random sampling. For each random sampling, 15 165 filaments are displaced at random positions on the ROSAT map. The 1σ uncertainties are estimated by computing a standard deviation of the 1000 random sample.