1999A&A...343..697R

A rudimentary analysis of the 21 rotation curves given by Rubin et al. (1980ApJ...238..471R) based on the hypothesis that V_rot=AR^α where (α,A) are constants particular to any given rotation curve, raised the further hypothesis that the distribution of the parameter ln(A) (estimated by linear regression on the rotation curves) has a discrete structure which, if representing an underlying real physical effect, would imply that the dynamics of spiral galaxies are constrained to occupy discrete states. The availability of the very large H_α rotation curve data base of spiral galaxies (Persic & Salucci, 1995ApJS...99..501P; PS hereafter) has provided an opportunity to conduct a strong test of this idea, and we find it confirmed at a level of almost certainty on the data analysed. Given the already well known strong relationship between rotational kinematics and luminosity properties of galaxies, this result implies that the luminosity evolution of spiral galaxies is constrained to occur on discretely defined surfaces so that, finally, a form of `cosmic coherence' for galaxy evolution appears to be suggested.