Stellar-to-gas mass ratio within r₅₀₀ vs. gas entropy at 0.2r₅₀₀ and the best fit in the upper panel, as well as the residuals normalized by the error bars in the lower panel. The symbols have the same meaning as those in Fig. 1. The data support the interpretation that heating from merging quenches the star-formation activity of galaxies in massive systems, and feedback from supernovae and/or radio galaxies drives a significant amount of gas to the regions beyond r₅₀₀ or, alternatively, a substantially higher stellar mass fraction in the ICL is present in nonrelaxed systems (e.g., Pierini et al. 2008).