Velocity gradient and brightness in disc galaxies

We quantify this relation by measuring the inner circular-velocity gradient d_R_V(0) for spiral and irregular galaxies with high-quality rotation curves. We find that d_R_V(0) correlates with the central surface brightness {mu}_0_ over more than two orders of magnitude in d_R_V(0) and four orders of magnitudes in {mu}_0_.

This is a scaling relation for disc galaxies. It shows that the central stellar density of a galaxy closely relates to the inner shape of the potential well, also for low-luminosity and low-surface-brightness galaxies that are expected to be dominated by dark matter.