Panel (a): Median and 68%C.I. of the noise marginalised HD S/N computed with realisation 94 by cutting the dataset at different epochs. The same cuts were applied to the real EPTA DR2 and the violins shown the HD S/N distribution. Panel (b): Marginalised posterior distributions of γ_GWB and log₁₀A_GWB obtained from the DR2full and DR2new version of realisation 94. As a reference, the median values and 2σ covariance principal axes obtained from the real data are displayed.