Fig. 2: Star-forming plane.

a Face-on and b edge-on view of the star-forming plane. The star-forming plane refers to the largely two-dimensional distribution of star formation rates (SFRs), neutral and molecular gas masses relative to the peak position of the star forming, neutral gas, and molecular gas sequence for a given stellar mass. Markers indicate the measured SFRs and gas masses of xGASS/xCOLD GASS observations with marker shapes and colors corresponding to different stellar masses (see legend). Regions bounded by the green, blue, and yellow isosurfaces include 10, 50, and 90% of galaxies (without the zero component) according to the fiducial model. Solid lines mark the intersections of the star-forming plane with the coordinate axes. The orientation of the star-forming plane is calculated via a principal component analysis based on the probability density within the 50% isosurface. The orientation of the star-forming plane is only weakly dependent on stellar mass.