Comparison of the S^–1 sample distribution in the P – R_p and F – R_p planes to highlight the irradiation desert. Left: distribution of the S^–1 sample in the P – R_p diagram along the edges obtained by Mazeh et al. (2016). The yellow triangles represent the 221 hot Neptunes within the S¹ sample according to the definition of Mazeh et al. (2016) in the P – R_p plane. The black dots represent all the planets that lie outside the desert. Right: distribution of the S¹ sample in the F – R_p plane. The orange and blue lines represent the lower and upper boundary obtained in Sect. 3.1 alongside their confidence bands (1σ). The yellow triangles show the 194 out of 221 objects that do not lie within the irradiation desert defined in this work. The yellow triangles used to designate the hot Neptunes in the P – R_p diagram still refer to the same planets in the right plot. The red stars indicate planets that fall within our defined boundaries but not within those outlined by Mazeh et al. (2016).