Thermal diffusivities (top panel) as a function of stellar radius and the ratio of linear IGW amplitudes obtained with real stellar thermal diffusivities to those obtained with profiles used in our main simulations (bottom panel) as a function of wave frequencies at the top of the radiation zone. The dotted lines in the top panel indicate the varying thermal diffusivity profiles used for our main simulations, whilst the solid lines indicate the realistic thermal diffusivities from MESA. In the bottom panel, the wavenumbers for all the waves have been set to 1. The initial radius for these IGWs was chosen at random from the middle of the radiation zone and the initial amplitude was set to unity.