Comparison of the cold molecular and Hα emitting gas. Left panel: molecular mass versus Hα luminosity. The molecular masses were taken from either IRAM 30m or APEX telescope observations (O’Sullivan et al. 2015; O’Sullivan et al. 2018b). We compare this relation with higher mass systems (BCGs). Observations from Edge (2001) and Salomé & Combes (2003) are plotted with inverted blue and yellow triangles, respectively. Upper limits from previous works are not included in this plot. A clear correlation between Hα luminosity and molecular gas masses is seen, in agreement with the previous detection from BCGs. This correlation is consistent with the top-down multiphase condensation and CCA rain. The gray dashed line corresponds to a linear fit considering only BCGs. Right panel: molecular mass versus Hα luminosity extracted from the same aperture as the CO measurements. The dashed gray line corresponds to the linear fit using measurements from BCGs. The CO molecular gas masses for BCGs are taken from Olivares et al. (2019) using ALMA observations, whereas Hα luminosities are measured using MUSE observations. BGGs showing Hα in absorption at the galaxy center are marked with circles.