Detection function map of the RV time-series of GJ 15 A. The white part corresponds to the area in the period—minimum mass space where additional signals could be detected if present in the data, i.e. p_i = 1, while the black region corresponds to the area where the detection probability is negligible, i.e. p_i = 0. The red circle marks the position in the parameter space of the planet GJ 15 A b.