Comparison between Boötes I, Galactic GCs, and field stars. Left: fraction of binaries with mass ratio q > 0.5 in the cores of GCs (Milone et al. 2012, 2016), compared with that in Boötes I. The red and yellow diamonds represent Boötes I, corresponding to the dynamical and stellar masses, respectively, from Martin et al. (2008) and Jenkins et al. (2021). GC masses are adopted from Baumgardt et al. (2020). Middle: binary fraction plotted against the concentration parameter, r_h/r_t. Radii are taken from the 2010 edition of the Harris (1996) catalog for GCs, and from Okamoto et al. (2012) and Belokurov et al. (2006) for Boötes I. Right: total binary fraction as a function of the primary-component mass. Gray dots correspond to Galactic field stars compiled in the review by Offner et al. (2023), and the green diamond indicates the binary fraction measured for the SMC field by Legnardi et al. (2025).