Measured midplane thermal pressure P _th of the diffuse gas relative to the two-phase thermal equilibrium pressure P _two, as a function of Σ _SFR. The points and error bars give the mean and standard deviations over t/ t _orb = 2–3 for each model. The dotted line, with a slope of −0.09, gives the best fit. Heating/cooling and mass exchange between warm and cold atomic phases enables the mean pressure to track the (radiation) energy input from star formation P _th∝ P _two∝Σ _SFR over more than two orders of magnitude in Σ _SFR.