Likelihood ratio ℓ (left) and marginalised posterior (right) obtained from 3 keV mock data in the optimistic scenario for a survey covering 1600 deg² with R = 500 and $P_{\mathrm{WN}}\simeq 2.4\times {10}^9{h}^{-3}{{\mathrm{Mpc}}^3{\mathrm{Jy}}^2\mathrm{sr}}^{-2}$. In the right panel, the dark-green and orange vertical lines denote the 95% credible regions, computed assuming uniform priors in m_WDM and $m_{\mathrm{WDM}}^{-1}$, respectively.