Comparison of the actual GLS periodogram of SOPHIE data (dark curve) and the periodograms obtained from simulated data sets not including a signal at that period. The ten periodograms exhibiting the strongest power at the vicinity of the detected signal among the 10 000 simulated cases are plotted in light grey. The horizontal lines are the 0.5, 0.1 and 0.01 p-value levels, computed as for Fig. 4.