Photospheric activity of main sequence stars in binary candidates of Gaia DR3 as a function of the rotational period. Red and blue markers indicate rotation periods reported by García et al. (2014a) and Santos et al. (2021), respectively. If measurements in both references are given, the Santos et al. (2021) value is shown. For comparison, the minimum and maximum S​_ph value of solar cycle 23 are shown as dashed horizontal lines. The red box frames the distinct group stars of short rotation periods and mostly super-solar levels of stellar activity. The labels a–h provide cross identification with the stars in Fig. 14 and Table 2.