Angular-momentum plane for disc galaxies

In particular, the baryonic relation (jbar-Mbar-fgas), arguably the most fundamental of the three, is followed not only by typical discs but also by galaxies with extreme properties, such as size and gas content, and by galaxies previously claimed to be outliers of the standard 2D j-M relations. The stellar relation (j*-M*-fgas) may be connected to the known j*-M* bulge fraction relation; however, we argue that the jbar-Mbar-fgas relation can originate from the radial variation in the star formation efficiency in galaxies, although it is not explained by current disc instability models.