FUNDAMENTAL MASS-SPIN-MORPHOLOGY RELATION OF SPIRAL GALAXIES

This work presents high-precision measurements of the specific baryon angular momentum j(b) contained in stars, atomic gas, and molecular gas, out to greater than or similar to 10 scale radii, in 16 nearby spiral galaxies of the THINGS sample. The accuracy of these measurements improves on existing studies by an order of magnitude, leading to the discovery of a strong correlation between the baryon mass M-b, j(b), and the bulge mass fraction beta, fitted by beta = -(0.34 +/- 0.03) lg (j(b)M(b)(-1)/[10(-7) kpc km s(-1) M-circle dot(-1)]) - (0.04 +/- 0.01) on the full sample range of 0 <= beta less than or similar to 0.3 and 10(9) M-circle dot < M-b < 10(11) M-circle dot. The corresponding relation for the stellar quantities M-* and j(*) is identical within the uncertainties. These M-j-beta relations likely originate from the proportionality between jM(-1) and the surface density of the disk that dictates its stability against (pseudo-) bulge formation. Using a cold dark matter model, we can approximately explain classical scaling relations, such as the fundamental plane of spiral galaxies, the Tully-Fisher relation, and the mass-size relation, in terms of the M-j(-beta) relation. These results advocate the use of mass and angular momentum as the most fundamental quantities of spiral galaxies.