The V c − σ 0 Relation of Galaxies

Courteau et al. (2007a) reported on the dependence of the ratio of a galaxy’s maximum circular velocity, Vc, to its central velocity dispersion, σ0, on morphology, or equivalently total light concentration. This Vc − σ0−concentration relation, which involves details about the local and global galaxy physics, poses a fundamental challenge for galaxy structure models. Furthermore, not only must these models reproduce the Vc − σ0 relation and its various dependences, they must simultaneously match other fundamental scaling relations such as the velocity-size-luminosity and color-luminosity relations of galaxies. We focus here on the interpretation of parameters that enter the Vc−σ0 relation to enable proper data-model comparisons and follow-up studies by galaxy modelers and observers.