Comparison of the S₃ sample distribution in the P – M_p and F – M_p planes to highlight the irradiation desert. Left: distribution of the S₃ sample in the P– M_p diagram along the edges obtained by Mazeh et al. (2016). The yellow dots represent the 110 hot Neptunes within S₃ according to the definition of Mazeh et al. (2016) in the P – M_p plane. The black dots represent planets outside the desert. Right: distribution of our sample in the F – M_p plane. The orange and blue lines represent the lower and upper boundary obtained in Sect. 3.2 alongside their confidence bands (1σ). The red dots show that 63 out of 110 objects experience an incident flux lower than 550 F_⊕. The yellow triangles used to designate the hot Neptunes in the P – M_p diagram still refer to the same planets in the right plot.