Averaged periodogram of RX J0440 data. In red, we show the combined model for ℳ₁ (left) and ℳ₂ (right), in purple, we show the power-law components, and in blue and orange we show the two Lorentzians (only one for ℳ₁) – each of which includes a constant white noise component. Dashed lines represent the median of the posterior predictive distribution, and lightly shaded solid lines correspond to twenty individual draws from the posterior predictive distribution, for each of the model components as well as the combined model.