Same as Fig. C.1 but for Γ, the polytropic index for the gas. Increasing Γ makes the gas profile less concentrated, as can be seen in the halo-profile plots (top right). If Γ is lowered then gas is more concentrated and the power spectrum of gas is boosted at small scales. Effects on power spectra that do not involve gas are much smaller. The same trends are seen in the electron-pressure profile and spectra involving the electron pressure, which are also sensitive to this parameter as the gas pressure is partly determined by the gas density.