Alfvén Mach number (upper panel) and flux density (for B_pl = 0 and 1 G for middle and lower panels, respectively) arising from SPI as a function of the stellar mass-loss rate (in solar units). The emission expected from Saur-Turnpenney’s model is shown in orange, and the emission expected from the Zarka-Lanz model is shown in blue. The overlap of the models is shown in brown. The dashed black line represents the assumed detection threshold of 100 μJy.