Probability distribution functions of the cosine of the angle between the reionisation patches and their corresponding filaments (top panel). Bottom panel: same PDFs are shown, but they are divided by the one of the model with ζ = 30 and log₁₀(T_vir) = 4.69897. Each of the models that only varied ζ is represented here, and all patches of their 101 runs are accumulated in both panels. The model with ζ = 30 and log₁₀(T_vir) = 4.69897 is also represented (top panel, in grey) with a rotation of filaments for comparison with total randomness.