Marginalised posterior (over σ) computed for the whole set of sky areas in the optimistic scenario, with R = 100 and P_WN ≃ 2.4 × 10¹⁰ h⁻³ Mpc³ Jy² sr⁻². Left: Posterior for a fixed β = 0 (uniform prior in w). Right: Result marginalised over β. The dashed lines of corresponding colours indicate the m_WDM threshold up to which CDM and WDM can be distinguished (95% CL). The dotted lines show the assumed prior distribution for w.