Analysis of the ESPRESSO residual time series. Panel a: GLS periodogram of the residuals of ESPRESSO RVs for HD 20794 once we subtract the signal at 18.3 d. We can see a double peak at 87 and 113 d, one peak being the 1 year alias of the other. Panel (b): GLS periodogram of the residuals of ESPRESSO RVs for HD 20794 after subtracting the signals at 18.3 d and 87 d. We can see some peaks at 4 and 40 d. The peak at 4 d probably comes from the sampling, while the peak at 40 d could be a signature of the stellar rotation period.