# Why does the torque curve of free shaft gas turbines keep gradually dropping as RPMs increase?

When i look at the output shaft torque curve of a free shaft gas turbine i can see that they are almost like an electric motor. It makes peak torque at very low rpm and then torque keeps gradually dropping. I know that in electric motors the torque drops due to back EMF as RPMs increase. In free shaft gas turbines, what causes this torque decrease as RPMs increase? For example the curve for AGT1500