Generalized Lomb–Scargle periodograms of the combined HARPS and HARPS-N datasets. The right and left columns cover two frequency ranges encompassing the 3 planetary signals (dotted vertical red lines), as well as the stellar rotation frequency and its first 2 harmonics (dotted vertical blue lines). From top to bottom: RV data, RV residuals after subtracting the stellar activity signal, RV residuals after subtracting the signals of the 3 transiting planets, BIS and FWHM of the CCF, S-index, and window function. The dashed horizontal red lines mark the 0.1 % false alarm probabilitiesas derived using the bootstrap technique. The red arrow in the lower panel marks the peak discussed in the main text.