Effect of varying ϵ₁, which governs deviations in halo concentration for low-mass haloes that have ejected their gas, on halo profiles (top right two panels), halo mass fractions (bottom right) and power spectra and responses (left column; top left two panels for matter spectra, bottom left two panels for pressure). Increasing ϵ₁ increases halo concentration and this generally boosts power. From the top right we see this has the largest impact for lower mass haloes because these have ejected most of their gas. From the left-hand panels, this has comparatively more of an impact on power spectra involving gas than on the other spectra. We can also see similar effects on spectra that involve the electron pressure.