250 μm monochromatic luminosity function of the SSA22 protocluster core region at z = 3.09. The blank field results at similar redshifts from single-dish (Lapi et al. 2011; Koprowski et al. 2017) or ALMA surveys (Gruppioni et al. 2020; Fujimoto et al. 2024) and the double power law (DPL) fits from Fujimoto et al. (2024) are also plotted. The vertical dashed and dotted lines mark the 90% and 50% completeness, respectively. Total infrared luminosities are converted to that at 250 μm by assuming a modified blackbody with a temperature of 35 K and an emissivity of 1.8.