Observed and modeled power spectra of solar activity. Upper panel: spectra based on the historical record of sunspot numbers (blue curve) and on the reconstruction from cosmogenic isotope data (Usoskin et al. 2016, red curve). Lower panel: spectrum obtained from one realization of the noisy normal form model (NNF model Cameron & Schüssler 2017a, blue curve). In both panels, the orange curve gives the median from 1000 realizations of the model, the green curve shows the corresponding 99.865% (3σ) upper percentile, and the yellow curve represents the maximum of the 1000 realizations.