Fe xvii line ratios for NGC 5044 (left) and NGC 5813 (right). The lines give the predicted (I_17.05 + I_17.10)/I_15.01 line ratio for different Mach numbers (0, 0.25, 0.5, and 0.75) from Monte Carlo simulations assuming isotropic turbulence. Note that these profiles have been re-scaled to the optically-thin (I_17.05 + I_17.10)/I_15.01 line ratio from Doron & Behar (2002). The data point in each plot is the measured line ratio derived from RGS.