a) Total flux L_tot/L_Edd emitted by the hot corona and b) intercepted soft photon luminosity L_s/L_Edd entering and cooling the hot corona. c) and d), like a) and b) but for the warm corona. e) Compton amplification ratio L_tot/L_s for the warm (bottom curve) and hot (top curve) coronae, respectively. The dotted line in e) is the expected value for a thick corona in radiative equilibrium above a passive disk. All the luminosities are in Eddington units assuming a black-hole mass of 1.4 × 10⁸ M_⊙. The error bars on L_obs and L_s have been estimated as on the order of 5%.