CO SLEDs of the PHz-IRAM sources (full red circles connected by a black solid line). The CO SLEDs of different types of galaxies normalized to the observed CO(3−2) intensity of each PHz-IRAM source are shown for comparison in each panel as dotted lines: the Milky Way (purple; Fixsen et al. 1999); SMGs (orange), QSO (brown), the prototypical starburst galaxy M 82 (green), and color-selected SFGs (CSG; blue) from Carilli & Walter (2013); and BzK galaxies at z ∼ 1.5 (cyan) from Daddi et al. (2015). The solid magenta line in each panel shows the SLED model from Narayanan & Krumholz (2014) obtained assuming the annotated SFR density in M_⊙ yr⁻¹ kpc⁻².