Apparent polytropic indices Γ_i, Γ_e, and Γ_l as functions of m and n. The critical values of 1, 4/3, and 5/3 are marked with white, yellow, and green contours, respectively. In regimes shown in red, the gas temperature increases with increasing density. In regimes shown in blue, the opposite happens. The values of Γ are shown irrespectively of the existence of a collapse solution, while the physical domain is shown in Fig. 3.