Detection limits of the RV residuals for the period of the assumed low-mass planet responsible for the LOFAR signal, after subtracting the best-fitting model consisting of the effect of GJ 1151 c and an additional quadratic polynomial. The black lines correspond to the minimum masses of the planetary signals as recovered by the simulations. The red line corresponds to the minimum mass of the average limiting semiamplitude along with its standard deviation limits in blue.