Bivariate distribution of the bolometric intensity I_bol and the absolute vertical magnetic field |B_z| in the center of the swirls identified on the surface layer at z = 0 km of the four stellar models. The distributions during the kinematic and saturation phases are shown in blue and orange, respectively. The vertical black dotted lines indicate the mean bolometric intensity in the intergranular (lower value) and granular (higher value) regions. The red shaded area indicates the identification range of magnetic bright feature (MBF) as defined by Riva et al. (2024).