Proton and neutron chemical potentials (rest mass subtracted) of BLh in the density-temperature plane at fixed Y_p = 0.08. The proton fraction Y_p = 0.08 is the equilibrium proton fraction at 4.6 ms after merger around the point x = 0.64 km, y = 12.76 km, z = 0 km, where ρ ∼ 5 × 10¹³ g cm⁻³, T_sim ∼ 10 MeV, and neutrinos dominate, while anti-neutrinos are suppressed (see also Figs. 1, 3 and 5). We notice that the colour bars are scaled differently.